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1

The Effects of Additional Action Observational Training for Functional Electrical Stimulation Treatment on Weight Bearing, Stability and Gait Velocity of Hemiplegic Patients  

PubMed Central

[Purpose] The purpose of this study was to evaluate the functional effects of additional action observational training for functional electrical stimulation treatment on weight bearing, stability and gait velocity of hemiplegic patients. [Subjects and Methods] Twenty subjects were randomized into two groups. Subjects more than six months post-stroke participated. Balance and gait velocity were measured at the baseline, and after six weeks of treatment. Both groups received functional electrical stimulation treatment. The experimental group additionally received action observational training. The paired t-test was used to analyze differences in the outcome measures between before and after the intervention. The difference between the groups was compared using the independent t-test. [Results] The experimental group showed significant increases in weight bearing (anterior·posterior, right·left) on the affected side, stability index and gait velocity. The control group showed only a significant increase in anterior·posterior weight bearing on the affected side. Moreover, according to the comparison of training effects between in the two groups, the variables of anterior·posterior weight bearing, stability index and gait velocity revealed a statistically significant difference. [Conclusion] Additional action observational training for functional electrical stimulation treatment should be considered as a therapeutic method in physical therapy for the improvement of weight bearing, stability index and gait velocity of hemiplegic patients. PMID:24259939

Park, Chang-Sik; Kang, Kwon-Young

2013-01-01

2

Influence of Body Weight Support on Normal Human Gait: Development of a Gait Retraining Strategy  

Microsoft Academic Search

The recovq of locomotion, following interactive training with graded weight support, in the adult spinal cat has led to the proposal that removal of body weight may be a therapeutic tool in human gait retraining. There would be bene- fits, however, in knowing normal responses of humans to partial weight bearing before applying this strategy to patients. In this study,

Barbeau B Arsenault; Hugues Barbeau; Bertrand Arsenault

1991-01-01

3

Aging and partial body weight support affects gait variability  

Microsoft Academic Search

BACKGROUND: Aging leads to increases in gait variability which may explain the large incidence of falls in the elderly. Body weight support training may be utilized to improve gait in the elderly and minimize falls. However, before initiating rehabilitation protocols, baseline studies are needed to identify the effect of body weight support on elderly gait variability. Our purpose was to

Anastasia Kyvelidou; Max J Kurz; Julie L Ehlers; Nicholas Stergiou

2008-01-01

4

Aging and partial body weight support affects gait variability  

PubMed Central

Background Aging leads to increases in gait variability which may explain the large incidence of falls in the elderly. Body weight support training may be utilized to improve gait in the elderly and minimize falls. However, before initiating rehabilitation protocols, baseline studies are needed to identify the effect of body weight support on elderly gait variability. Our purpose was to determine the kinematic variability of the lower extremities in young and elderly healthy females at changing levels of body weight support during walking. Methods Ten young and ten elderly females walked on a treadmill for two minutes with a body weight support (BWS) system under four different conditions: 1 g, 0.9 g, 0.8 g, and 0.7 g. Three-dimensional kinematics was captured at 60 Hz with a Peak Performance high speed video system. Magnitude and structure of variability of the sagittal plane angular kinematics of the right lower extremity was analyzed using both linear (magnitude; standard deviations and coefficient of variations) and nonlinear (structure; Lyapunov exponents) measures. A two way mixed ANOVA was used to evaluate the effect of age and BWS on variability. Results Linear analysis showed that the elderly presented significantly more variability at the hip and knee joint than the young females. Moreover, higher levels of BWS presented increased variability at all joints as found in both the linear and nonlinear measures utilized. Conclusion Increased levels of BWS increased lower extremity kinematic variability. If the intent of BWS training is to decrease variability in gait patterns, this did not occur based on our results. However, we did not perform a training study. Thus, it is possible that after several weeks of training and increased habituation, these initial increased variability values will decrease. This assumption needs to be addressed in future investigation with both "healthy" elderly and elderly fallers. In addition, it is possible that BWS training can have a positive transfer effect by bringing overground kinematic variability to healthy normative levels, which also needs to be explored in future studies. PMID:18803851

Kyvelidou, Anastasia; Kurz, Max J; Ehlers, Julie L; Stergiou, Nicholas

2008-01-01

5

Regional differences in trabecular BMD and micro-architecture of weight-bearing bone under habitual gait loading—A pQCT and microCT study in human cadavers  

Microsoft Academic Search

This study used both multi-slice pQCT and microCT to investigate regional changes in bone mineral density and structural parameters in the ultradistal tibia and in the mid-femoral neck under habitual gait loading. Twenty cadavers with 2 females and 18 males aged 70.8 ± 8.5 were used in this study. Seventy-two cylindrical bone cores with 5 mm in diameter and 10 mm in

Y. M. Lai; L. Qin; H. Y. Yeung; K. K. H. Lee; K. M. Chan

2005-01-01

6

The use of body weight support on ground level: an alternative strategy for gait training of individuals with stroke  

PubMed Central

Background Body weight support (BWS) systems on treadmill have been proposed as a strategy for gait training of subjects with stroke. Considering that ground level is the most common locomotion surface and that there is little information about individuals with stroke walking with BWS on ground level, it is important to investigate the use of BWS on ground level in these individuals as a possible alternative strategy for gait training. Methods Thirteen individuals with chronic stroke (four women and nine men; mean age 54.46 years) were videotaped walking on ground level in three experimental conditions: with no harness, with harness bearing full body weight, and with harness bearing 30% of full body weight. Measurements were recorded for mean walking speed, cadence, stride length, stride speed, durations of initial and terminal double stance, single limb support, swing period, and range of motion of ankle, knee, and hip joints; and foot, shank, thigh, and trunk segments. Results The use of BWS system leads to changes in stride length and speed, but not in stance and swing period duration. Only the hip joint was influenced by the BWS system in the 30% BWS condition. Shank and thigh segments presented less range of motion in the 30% BWS condition than in the other conditions, and the trunk was held straighter in the 30% BWS condition than in the other conditions. Conclusion Individuals with stroke using BWS system on ground level walked slower and with shorter stride length than with no harness. BWS also led to reduction of hip, shank, and thigh range of motion. However, this system did not change walking temporal organization and body side asymmetry of individuals with stroke. On the other hand, the BWS system enabled individuals with chronic stroke to walk safely and without physical assistance. In interventions, the physical therapist can watch and correct gait pattern in patients' performance without the need to provide physical assistance. PMID:19951435

2009-01-01

7

Automatic Gait Recognition Using Weighted Binary Pattern on Video  

Microsoft Academic Search

Human identification by recognizing the spontaneous gait recorded in real-world setting is a tough and not yet fully resolved problem in biometrics research. Several issues have contributed to the difficulties of this task. They include various poses, different clothes, moderate to large changes of normal walking manner due to carrying diverse goods when walking, and the uncertainty of the environments

Worapan Kusakunniran; Qiang Wu; Hongdong Li; Jian Zhang

2009-01-01

8

Development of body weight support gait training system using antagonistic bi-articular muscle model.  

PubMed

The purpose of this study is to develop a body weight support gait training system for stroke and spinal cord injury. This system consists of a powered orthosis, treadmill and equipment of body weight support. Attachment of the powered orthosis is able to fit subject who has difference of body size. This powered orthosis is driven by pneumatic McKibben actuator. Actuators are arranged as pair of antagonistic bi-articular muscle model and two pairs of antagonistic mono-articular muscle model like human musculoskeletal system. Part of the equipment of body weight support suspend subject by wire harness, and body weight of subject is supported continuously by counter weight. The powered orthosis is attached equipment of body weight support by parallel linkage, and movement of the powered orthosis is limited at sagittal plane. Weight of the powered orthosis is compensated by parallel linkage with gas-spring. In this study, we developed system that has orthosis powered by pneumatic McKibben actuators and equipment of body weight support. We report detail of our developed body weight support gait training system. PMID:21095773

Shibata, Yoshiyuki; Imai, Shingo; Nobutomo, Tatsuya; Miyoshi, Tasuku; Yamamoto, Shin-Ichiroh

2010-01-01

9

Gait training with partial body weight support during overground walking for individuals with chronic stroke: a pilot study  

PubMed Central

Background It is not yet established if the use of body weight support (BWS) systems for gait training is effective per se or if it is the combination of BWS and treadmill that improves the locomotion of individuals with gait impairment. This study investigated the effects of gait training on ground level with partial BWS in individuals with stroke during overground walking with no BWS. Methods Twelve individuals with chronic stroke (53.17 ± 7.52 years old) participated of a gait training program with BWS during overground walking, and were evaluated before and after the gait training period. In both evaluations, individuals were videotaped walking at a self-selected comfortable speed with no BWS. Measurements were obtained for mean walking speed, step length, stride length and speed, toe-clearance, durations of total double stance and single-limb support, and minimum and maximum foot, shank, thigh, and trunk segmental angles. Results After gait training, individuals walked faster, with symmetrical steps, longer and faster strides, and increased toe-clearance. Also, they displayed increased rotation of foot, shank, thigh, and trunk segmental angles on both sides of the body. However, the duration of single-limb support remained asymmetrical between each side of the body after gait training. Conclusions Gait training individuals with chronic stroke with BWS during overground walking improved walking in terms of temporal-spatial parameters and segmental angles. This training strategy might be adopted as a safe, specific and promising strategy for gait rehabilitation after stroke. PMID:21864373

2011-01-01

10

The Combined Effects of Body Weight Support and Gait Speed on Gait Related Muscle Activity: A Comparison between Walking in the Lokomat Exoskeleton and Regular Treadmill Walking  

PubMed Central

Background For the development of specialized training protocols for robot assisted gait training, it is important to understand how the use of exoskeletons alters locomotor task demands, and how the nature and magnitude of these changes depend on training parameters. Therefore, the present study assessed the combined effects of gait speed and body weight support (BWS) on muscle activity, and compared these between treadmill walking and walking in the Lokomat exoskeleton. Methods Ten healthy participants walked on a treadmill and in the Lokomat, with varying levels of BWS (0% and 50% of the participants’ body weight) and gait speed (0.8, 1.8, and 2.8 km/h), while temporal step characteristics and muscle activity from Erector Spinae, Gluteus Medius, Vastus Lateralis, Biceps Femoris, Gastrocnemius Medialis, and Tibialis Anterior muscles were recorded. Results The temporal structure of the stepping pattern was altered when participants walked in the Lokomat or when BWS was provided (i.e. the relative duration of the double support phase was reduced, and the single support phase prolonged), but these differences normalized as gait speed increased. Alternations in muscle activity were characterized by complex interactions between walking conditions and training parameters: Differences between treadmill walking and walking in the exoskeleton were most prominent at low gait speeds, and speed effects were attenuated when BWS was provided. Conclusion Walking in the Lokomat exoskeleton without movement guidance alters the temporal step regulation and the neuromuscular control of walking, although the nature and magnitude of these effects depend on complex interactions with gait speed and BWS. If normative neuromuscular control of gait is targeted during training, it is recommended that very low speeds and high levels of BWS should be avoided when possible. PMID:25226302

Van Kammen, Klaske; Boonstra, Annemarijke; Reinders-Messelink, Heleen; den Otter, Rob

2014-01-01

11

Foot Loading Characteristics of Different Graduations of Partial Weight Bearing  

ERIC Educational Resources Information Center

Limited weight bearing of the lower extremity is a commonly applied procedure in orthopaedic rehabilitation after reconstructive forefoot surgery, trauma surgery and joint replacement. The most frequent limitations are given as percentage of body weight (BW) and represent 10 or 50% BW. The extent of foot loading under these graduations of partial…

Gusinde, Johannes; Pauser, Johannes; Swoboda, Bernd; Gelse, Kolja; Carl, Hans-Dieter

2011-01-01

12

Improvement of gait ability with a short-term intensive gait rehabilitation program using body weight support treadmill training in community dwelling chronic poststroke survivors  

PubMed Central

[Purpose] Most previous studies have shown that body weight support treadmill training (BWSTT) can improve gait speed poststroke patients. The purpose of this study was to evaluate effectiveness of a short-term intensive program using BWSTT among community dwelling poststroke survivors. [Subjects] Eighteen subjects participated in this study. The treatment group was composed of 10 subjects (2 women; 8 men; mean age, 59.1 ± 12.5?years; time since stroke onset, 35.3 ± 33.2 months), whereas the control group was made up of 8 subjects (3 women; 5 men; mean age, 59.8 ± 6.3?years; time since stroke onset, 39.3 ± 27.3 months). [Methods] The treatment group received BWSTT 3 times a week for 4 weeks (a total of 12 times), with each session lasting 20 minutes. The main outcome measures were maximum gait speed on a flat floor, cadence, and step length. [Results] No differences were observed in the baseline clinical data between the 2 groups. The gait speed in the treatment group was significantly improved compared with that in the control by 2-way ANOVA, while the other parameters showed no significant interaction. [Conclusion] These results suggested that short-term intensive gait rehabilitation using BWSTT was useful for improving gait ability among community dwelling poststroke subjects. PMID:25642063

Takao, Toshifumi; Tanaka, Naoki; Iizuka, Noboru; Saitou, Hideyuki; Tamaoka, Akira; Yanagi, Hisako

2015-01-01

13

Excess Body Weight Loss is Associated with Nonpathological Gait Patterns in Women 4 to 5 Years After Bariatric Surgery  

PubMed Central

Background This study examined relationships between excess body weight (EBW) loss and current gait and functional status in women 5 years after Roux-en-Y gastric bypass surgery. Methods Gait data were analyzed in nine female bariatric patients for relationships with longitudinal changes in weight, body composition, and physical function assessed by the Short Musculoskeletal Functional Assessment (SMFA) questionnaire and the timed “get-up-and-go” (TGUG) test. Gait characteristics in the bariatric sample were also compared to an age- and BMI-matched nonsurgical reference sample from the Fels Longitudinal Study. Results Bariatric patients lost an average of 36.4 kg (61.1 %) of EBW between preoperative and 5-year follow-up visits (P <0.01); SMFA function index scores and TGUG times also decreased (both P <0.01). Degree of EBW loss was correlated with less time spent in initial double support and more time in single support (both P =0.02), and for all gait variables, the bariatric sample fell within the 95 % confidence intervals of gait/EBW relationships in the reference sample. Conclusions Gait and function 5 years after bariatric surgery were characteristic of current weight, not preoperative obesity, suggesting that substantial, sustained recovery of physical function is possible with rapid surgical weight loss. PMID:24008625

Laughlin, Richard T.; Teel, Donovan D.; Sherwood, Richard J.; Duren, Dana L.

2014-01-01

14

Overground body-weight-supported gait training for children and youth with neuromuscular impairments.  

PubMed

The aim of this investigation was to determine if body-weight-supported (BWS) overground gait training has the potential to improve the walking abilities of children and youth with childhood onset motor impairments and intellectual disabilities. Eight participants (mean age of 16.3 years) completed 12 weeks of BWS overground gait training that was performed two times a week. BWS was provided during the training sessions by an overhead harness system that rolls overground. There was a significant improvement in the preferred walking speed after the training (p < .01; pre = 0.51 ± 0.2 m/s; post = 0.67 ± 0.3 m/s; Cohen's d = 0.80) and cadence (p = .04; pre = 37 ± 7 steps/min; post = 43 ± 8 steps/min; Cohen's d = 0.94). Our results indicate that overground BWS gait training may be an effective treatment strategy for improving the preferred walking speed of children and youth with motor impairments. PMID:23477615

Kurz, Max J; Stuberg, Wayne; Dejong, Stacey; Arpin, David J

2013-08-01

15

Geometry of a Weight-Bearing and Non-Weight-Bearing Bone in the Legs of Young, Old, and Very Old Men  

Microsoft Academic Search

Bone geometry is an important determinant of bone strength and is influenced by muscle pull and weight-bearing. Muscle mass\\u000a and exposure to weight-bearing decrease with age and thus the purpose of the study was to compare bone geometry of the weight-bearing\\u000a (tibia) and non-weight-bearing (fibula) bones of the leg in different age groups. Magnetic resonance images of the right leg

Chris J. McNeil; Graydon H. Raymer; Timothy J. Doherty; Greg D. Marsh; Charles L. Rice

2009-01-01

16

Temporospatial and kinematic gait alterations during treadmill walking with body weight suspension.  

PubMed

Our purpose was to analyze the effects of selected levels of body weight support (BWS) on lower extremity kinematics of normal subjects at a predetermined treadmill speed. Seventeen non-disabled volunteers walked on a treadmill at 1.25 ms(-1). Temporospatial and kinematic data were collected while various support levels were applied (Minimal, 10, 30, 50 and 70% BWS). Compared to 10% BWS, significant temporospatial and kinematic changes were induced by 50 and 70% BWS. Fewer differences were induced by 30% BWS compared to 10% BWS. We concluded that gait patterns of unimpaired subjects are significantly changed by 50 and 70% BWS. PMID:12770637

Threlkeld, A Joseph; Cooper, Lance D; Monger, Brock P; Craven, Aric N; Haupt, Howard G

2003-06-01

17

Weights and hematology of wild black bears during hibernation  

USGS Publications Warehouse

We compared weights and hematological profiles of adult (greater than 3-yr-old) female black bears (Ursus americanus) during hibernation (after 8 January). We handled 28 bears one to four times (total of 47) over 4 yr of varying mast and berry production. Mean weight of lactating bears was greater (P less than 0.0001) than that of non-lactating females. White blood cells (P less than 0.05) and mean corpuscular volume (P = 0.005) also differed between lactating and non-lactating bears. Hemoglobin (P = 0.006) and mean corpuscular hemoglobin concentration (P = 0.02) varied among years; values were lowest during 1975, following decreased precipitation and the occurrence of a second year of mast and berry crop shortages in a three-year period. Significant (P less than 0.05) interaction between reproductive status (lactating versus non-lactating) and study year for hemoglobin, red blood cells, and packed cell volume, and increased mean corpuscular volume, suggested a greater nutritional challenge for lactating females compared to non-lactating females during the 1975 denning season. Our data suggest that hematological characteristics of denning bears may be more sensitive than weights as indicators of annual changes in nutritional status; however, other influential factors, in addition to mast and berry crop production, remain to be examined.

DelGiudice, Glenn D.; Rogers, Lynn L.; Allen, Arthur W.; Seal, U.S.

1991-01-01

18

Image based weighted center of proximity versus directly measured knee contact location during simulated gait.  

PubMed

To understand the mechanical consequences of knee injury requires a detailed analysis of the effect of that injury on joint contact mechanics during activities of daily living. Three-dimensional (3D) knee joint geometric models have been combined with knee joint kinematics to dynamically estimate the location of joint contact during physiological activities-using a weighted center of proximity (WCoP) method. However, the relationship between the estimated WCoP and the actual location of contact has not been defined. The objective of this study was to assess the relationship between knee joint contact location as estimated using the image-based WCoP method, and a directly measured weighted center of contact (WCoC) method during simulated walking. To achieve this goal, we created knee specific models of six human cadaveric knees from magnetic resonance imaging. All knees were then subjected to physiological loads on a knee simulator intended to mimic gait. Knee joint motion was captured using a motion capture system. Knee joint contact stresses were synchronously recorded using a thin electronic sensor throughout gait, and used to compute WCoC for the medial and lateral plateaus of each knee. WCoP was calculated by combining knee kinematics with the MRI-based knee specific model. Both metrics were compared throughout gait using linear regression. The anteroposterior (AP) location of WCoP was significantly correlated with that of WCoC on both tibial plateaus in all specimens (p<0.01, 95% confidence interval of Pearson?s coefficient r>0), but the correlation was not significant in the mediolateral (ML) direction for 4/6 knees (p>0.05). Our study demonstrates that while the location of joint contact obtained from 3D knee joint contact model, using the WCoP method, is significantly correlated with the location of actual contact stresses in the AP direction, that relationship is less certain in the ML direction. PMID:24837219

Wang, Hongsheng; Chen, Tony; Koff, Matthew F; Hutchinson, Ian D; Gilbert, Susannah; Choi, Dan; Warren, Russell F; Rodeo, Scott A; Maher, Suzanne A

2014-07-18

19

Gait analysis and electromyography in fixed- and mobile-bearing total knee replacement: a prospective, comparative study  

Microsoft Academic Search

Purpose  The theoretical superiority of mobile-bearing total knee arthroplasties (TKAs) has not yet been proven in clinical studies.\\u000a The aim of the current study was to compare and to analyse in a patient population that had received either a fixed or a mobile\\u000a TKA differences in gait analysis electromyography and clinical scores.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  In a prospective, randomized, patient- and observer-blinded clinical study,

Carsten O. Tibesku; Kiriakos Daniilidis; Adrian Skwara; Tobias Dierkes; Dieter Rosenbaum; Susanne Fuchs-Winkelmann

20

The use of body weight support on ground level: an alternative strategy for gait training of individuals with stroke  

Microsoft Academic Search

BACKGROUND: Body weight support (BWS) systems on treadmill have been proposed as a strategy for gait training of subjects with stroke. Considering that ground level is the most common locomotion surface and that there is little information about individuals with stroke walking with BWS on ground level, it is important to investigate the use of BWS on ground level in

Catarina O Sousa; José A Barela; Christiane L Prado-Medeiros; Tania F Salvini; Ana MF Barela

2009-01-01

21

Eccentric exercise training as a countermeasure to non-weight-bearing soleus muscle atrophy  

NASA Technical Reports Server (NTRS)

This investigation tested whether eccentric resistance training could prevent soleus muscle atrophy during non-weight bearing. Adult female rats were randomly assigned to either weight bearing +/- intramuscular electrodes or non-weight bearing +/- intramuscular electrodes groups. Electrically stimulated maximal eccentric contractions were performed on anesthetized animals at 48-h intervals during the 10-day experiment. Non-weight bearing significantly reduced soleus muscle wet weight (28-31 percent) and noncollagenous protein content (30-31 percent) compared with controls. Eccentric exercise training during non-weight bearing attenuated but did not prevent the loss of soleus muscle wet weight and noncollagenous protein by 77 and 44 percent, respectively. The potential of eccentric exercise training as an effective and highly efficient counter-measure to non-weight-bearing atrophy is demonstrated in the 44 percent attenuation of soleus muscle noncollagenous protein loss by eccentric exercise during only 0.035 percent of the total non-weight-bearing time period.

Kirby, Christopher R.; Ryan, Mirelle J.; Booth, Frank W.

1992-01-01

22

Weight-Bearing Physical Activity among Girls and Mothers: Relationships to Girls’ Weight Status  

Microsoft Academic Search

Objective: To assess weight-bearing physical activity (WBPA) barriers, benefits, self-efficacy, social influence, and behaviors [WBPA and physical activity (PA)] among girls and their mothers according to girls’ weight status (nonoverweight vs. overweight).Research Methods and Procedures: Participants were 9- to 11-year-old girls (n = 295) and their mothers who participated in the baseline assessment of a nutrition and PA intervention trial.

Jayne A. Fulkerson; Simone A. French; Mary Story; Peter J. Hannan; Dianne Neumark-Sztainer; John H. Himes

2004-01-01

23

Using Gait as a Biometric, via Phase-weighted Magnitude Spectra  

Microsoft Academic Search

Abstract. Gait is a ,biometric which ,is subject ,to increasing ,interest. Current approaches,include modelling ,gait as a ,spatio-temporal sequence ,and ,as an articulated model. By considering legs only, gait can be considered to be the motion,of interlinked pendula. We describe how,the Hough transform is used to extract the lines which represent legs in sequences,of video,images. The change in inclination of

David Cunado; Mark S. Nixon; John N. Carter

1997-01-01

24

Weight bearing influence on knee joint bony contact movements: an in vivo video-fluoroscopy study.  

PubMed

In order to understand the effects of body weight-bearing on knee joint bony contact movements, a video-fluoroscopic digitizing system with in vivo human knee extension-flexion motions of 12 healthy adults under body weight-bearing and non-weight-bearing conditions was studied. These 12 subjects were equally separated into two groups consisting of a body weight-bearing group and a non-weight-bearing group. Video-fluoroscopic images were digitized to get three parameters from the knee joint bony geometry. These three parameters were the radius of rotation, the are length of rotation, and the contact point of the tibiofemoral joint, and they were used to decide the knee joint bony contact status of the sliding, spinning and rocking motions. The results showed that the knee bony contact movements under body weight-bearing conditions had about 4 times the incidence rate of the sliding motion under non-weight-bearing conditions. The incidence rate of the sliding motion was greatest when the knee flexion was less than 30 degrees. The knee bony contact movements under non-weight-bearing conditions had a larger spinning motion incidence rate and smaller rocking motion incidence rate than they did under weight-bearing conditions. The larger spinning motion incidence rate when the knee joint flexion was greater than 60 degrees. In conclusion, the body weight-bearing factor should be considered in studying knee joint bony contact movements. PMID:9208483

Cheng, C K; Yao, N K; Liu, H C

1997-01-01

25

Changes in skeletal muscle gene expression consequent to altered weight bearing  

NASA Technical Reports Server (NTRS)

Skeletal muscle is a dynamic organ that adapts to alterations in weight bearing. This brief review examines changes in muscle gene expression resulting from the removal of weight bearing by hindlimb suspension and from increased weight bearing due to eccentric exercise. Acute (less than or equal to 2 days) non-weight bearing of adult rat soleus muscle alters only the translational control of muscle gene expression, while chronic (greater than or equal to 7 days) removal of weight bearing appears to influence pretranslational, translational, and posttranslational mechanisms of control. Acute and chronic eccentric exercise are associated with alterations of translational and posttranslational control, while chronic eccentric training also alters the pretranslational control of muscle gene expression. Thus alterations in weight bearing influence multiple sites of gene regulation.

Booth, F. W.; Kirby, C. R.

1992-01-01

26

Gait trajectory planning and simulation for the powered gait orthosis  

Microsoft Academic Search

Body weight supported treadmill training (BWSTT) has been conformed to be an effective gait rehabilitation therapy for patients with locomotor disfunction of the lower limbs. A powered gait orthosis (PGO) is being developed, which can guide the patient's legs to move in a preprogrammed physiological gait pattern during BWSTT. This paper proposes a physiological gait trajectory planning method for the

Qiyuan Wang; Jinwu Qian; Yanan Zhang; Linyong Shen; Zhen Zhang; Zhiguo Feng

2007-01-01

27

Partial weight bearing after surgery for fractures of the lower extremity – is it achievable?  

Microsoft Academic Search

Partial weight bearing is a generally accepted principle of rehabilitation following trauma or reconstructive surgery of the lower extremity. Individual dynamic loads during partial weight bearing to a given load level of 200N were compared in 23 patients who had sustained a fracture of the lower extremity and 11 healthy volunteers using dynamic sole pressure measurements. Excessive dynamic loading compared

Attila Vasarhelyi; Tobias Baumert; Christoph Fritsch; Werner Hopfenmüller; Georg Gradl; Thomas Mittlmeier

2006-01-01

28

The Effects of Different Gait Speeds and Lower Arm Weight on the Activities of the Latissimus Dorsi, Gluteus Medius, and Gluteus Maximus Muscles  

PubMed Central

[Purpose] This study researched the effects of different gait speeds and lower arm weight on the activities of the latissimus dorsi, gluteus medius, and gluteus maximus muscles. [Subjects] Fourteen healthy adult men participated in this study. [Methods] All the participants carried out walking on a treadmill at speeds of 3.5?km/h and 5.5?km/h for half a minute. During treadmill gait, electromyographic activity muscle was measured of the latissimus dorsi, gluteus medius and gluteus maximus. [Result] There were significant differences in the muscle activities due to changes in gait speed and lower arm load in the latissimus dorsi and gluteus maximus, but there were no significant differences in the muscle activities of the gluteus medius. [Conclusion] According to our results, arm swing is related to increasing gait speed, and lower arm load is influences the muscle activity of the lower extremities through the posterior oblique sling system. PMID:24396216

Kim, Tae-young; Yoo, Won-gyu; An, Duk-hyun; Oh, Jae-seop; Shin, Seung-je

2013-01-01

29

Kinematic Analysis of Healthy Hips during Weight-Bearing Activities by 3D-to-2D Model-to-Image Registration Technique.  

PubMed

Dynamic hip kinematics during weight-bearing activities were analyzed for six healthy subjects. Continuous X-ray images of gait, chair-rising, squatting, and twisting were taken using a flat panel X-ray detector. Digitally reconstructed radiographic images were used for 3D-to-2D model-to-image registration technique. The root-mean-square errors associated with tracking the pelvis and femur were less than 0.3?mm and 0.3° for translations and rotations. For gait, chair-rising, and squatting, the maximum hip flexion angles averaged 29.6°, 81.3°, and 102.4°, respectively. The pelvis was tilted anteriorly around 4.4° on average during full gait cycle. For chair-rising and squatting, the maximum absolute value of anterior/posterior pelvic tilt averaged 12.4°/11.7° and 10.7°/10.8°, respectively. Hip flexion peaked on the way of movement due to further anterior pelvic tilt during both chair-rising and squatting. For twisting, the maximum absolute value of hip internal/external rotation averaged 29.2°/30.7°. This study revealed activity dependent kinematics of healthy hip joints with coordinated pelvic and femoral dynamic movements. Kinematics' data during activities of daily living may provide important insight as to the evaluating kinematics of pathological and reconstructed hips. PMID:25506056

Hara, Daisuke; Nakashima, Yasuharu; Hamai, Satoshi; Higaki, Hidehiko; Ikebe, Satoru; Shimoto, Takeshi; Hirata, Masanobu; Kanazawa, Masayuki; Kohno, Yusuke; Iwamoto, Yukihide

2014-01-01

30

Bears  

NSDL National Science Digital Library

What are the characteristics of grizzly/brown bears and black bears? As you view the websites, please use this chart to record what you are learning about grizzly bears and black bears. For each bear, you should list 5 characteristics. Grizzly Bear and Black Bear Chart We will first begin by learning about black bears. Please go to these websites to learn some important facts about black bears. Black Bears Facts and Image Black Bear Facts for Kids Now that you have learned ...

Bledsoe, Miss

2011-04-07

31

Weight-bearing locomotion in the developing opossum, Monodelphis domestica following spinal transection: remodeling of neuronal circuits caudal to lesion.  

PubMed

Complete spinal transection in the mature nervous system is typically followed by minimal axonal repair, extensive motor paralysis and loss of sensory functions caudal to the injury. In contrast, the immature nervous system has greater capacity for repair, a phenomenon sometimes called the infant lesion effect. This study investigates spinal injuries early in development using the marsupial opossum Monodelphis domestica whose young are born very immature, allowing access to developmental stages only accessible in utero in eutherian mammals. Spinal cords of Monodelphis pups were completely transected in the lower thoracic region, T10, on postnatal-day (P)7 or P28 and the animals grew to adulthood. In P7-injured animals regrown supraspinal and propriospinal axons through the injury site were demonstrated using retrograde axonal labelling. These animals recovered near-normal coordinated overground locomotion, but with altered gait characteristics including foot placement phase lags. In P28-injured animals no axonal regrowth through the injury site could be demonstrated yet they were able to perform weight-supporting hindlimb stepping overground and on the treadmill. When placed in an environment of reduced sensory feedback (swimming) P7-injured animals swam using their hindlimbs, suggesting that the axons that grew across the lesion made functional connections; P28-injured animals swam using their forelimbs only, suggesting that their overground hindlimb movements were reflex-dependent and thus likely to be generated locally in the lumbar spinal cord. Modifications to propriospinal circuitry in P7- and P28-injured opossums were demonstrated by changes in the number of fluorescently labelled neurons detected in the lumbar cord following tracer studies and changes in the balance of excitatory, inhibitory and neuromodulatory neurotransmitter receptors' gene expression shown by qRT-PCR. These results are discussed in the context of studies indicating that although following injury the isolated segment of the spinal cord retains some capability of rhythmic movement the mechanisms involved in weight-bearing locomotion are distinct. PMID:23951105

Wheaton, Benjamin J; Noor, Natassya M; Whish, Sophie C; Truettner, Jessie S; Dietrich, W Dalton; Zhang, Moses; Crack, Peter J; Dziegielewska, Katarzyna M; Saunders, Norman R

2013-01-01

32

Osteoporosis Knowledge, Calcium Intake, and Weight-Bearing Physical Activity in Three Age Groups of Women.  

ERIC Educational Resources Information Center

Determined the extent and integration of osteoporosis knowledge in three age groups of women, comparing knowledge to calcium intake and weight bearing physical activity (WBPA). Overall calcium intake was relatively high. There were no differences in knowledge, calcium intake, or WBPA by age, nor did knowledge predict calcium intake and WBPA. None…

Terrio, Kate; Auld, Garry W.

2002-01-01

33

Optimal weight design of rotor systems with oil-film bearings subjected to frequency constraints  

Microsoft Academic Search

The purpose of this study is to investigate optimal weight design of rotors. The analysis results of this work for dynamic analysis of rotors are compared to those available in the literature. An excellent agreement is observed, which validates the formulation and implementation of the model developed. Further analysis is conducted for rotors with oil-film bearings. The stability of the

Yih-Hwang Lin; Sheng-Cheng Lin

2001-01-01

34

Periprosthetic bone mineral density and fixation of the uncemented CLS stem related to different weight bearing regimes  

PubMed Central

Background and purpose There is no consensus on the best rehabilitation regime after uncemented total hip arthroplasty. Theoretically, bone ingrowth into the implant should benefit from initial partial weight bearing. We investigated whether the degree of postoperative weight bearing influences the periprosthetic bone mineral density (BMD) and/or the stability of the CLS stem. Patients and methods 38 patients received an uncemented CLS stem and were randomized to either unrestricted postoperative weight bearing or to partial weight bearing for 3 months. Periprosthetic BMD was measured in the 7 Gruen zones with DXA and the stability of the femoral stem was assessed by radiostereometric analysis (RSA) after surgery and at 3, 12, 24, and 60 months. Results Periprosthetic BMD was not influenced by the type of postoperative weight bearing. BMD was reduced by 8–15% in all Gruen zones at 3 months. Restoration toward initial BMD was observed in all zones except in zone 7 (calcar region), where BMD was reduced by 22% at 5 years. Immediate weight bearing after surgery had no influence on the stability of the CLS stem, as assessed by RSA. Interpretation Immediate full weight bearing after uncemented total hip arthroplasty is safe. There is no difference in the periprosthetic BMD or in stability of the stem as measured by RSA compared to partial weight bearing for 3 months. BMD is reduced by more than 20% in the calcar region around a CLS stem after 5 years. PMID:20446828

Mattsson, Per; Milbrink, Jan; Larsson, Sune; Mallmin, Hans

2010-01-01

35

The impact of adding weight-bearing exercise versus nonweight bearing programs to the medical treatment of elderly patients with osteoporosis  

PubMed Central

Background: Osteoporosis is a major public health problem affecting the elderly population, particularly women. The objective of the study was to evaluate the effects of adding weight-bearing exercise as opposed to nonweight-bearing programs to the medical treatment of bone mineral density (BMD) and health-related quality of life (HRQoL) of elderly patients with osteoporosis. Materials and Methods: Participating in the study were 40 elderly osteoporotic patients (27 females and 13 males), with ages ranging from 60 to 67 years, who were receiving medical treatment for osteoporosis. They were assigned randomly into two groups: Group-I: Twenty patients practiced weight-bearing exercises. Group-II: Twenty patients did nonweight-bearing exercises. All patients trained for 45-60 min/session, two sessions/week for 6 months. BMD of the lumbar spine, right neck of femur, and right distal radial head of all patients were measured by dual-energy X-ray absorptiometry before and after both treatment programs. In addition, the QoL was measured by means of the HRQoL “ECOS-16” questionnaire. Results: T-tests proved that mean values of BMD of the lumbar spine, right neck of femur and right distal radial head were significantly increased in both groups with greater improvement in the weight-bearing group. The QoL was significantly improved in both groups, but the difference between them was not significant. Conclusion: Addition of weight-bearing exercise program to medical treatment increases BMD more than nonweight-bearing exercise in elderly subjects with osteoporosis. Furthermore, both weight-bearing and nonweight-bearing exercise programs significantly improved the QoL of patients with osteoporosis. PMID:25374469

Shanb, Alsayed A.; Youssef, Enas F.

2014-01-01

36

EMG Activity of the Abductor Hallucis Muscle during Foot Arch Exercises Using Different Weight Bearing Postures  

PubMed Central

[Purpose] This study examined the effects of different weight-bearing postures on the activation of the abductor hallucis muscle during foot-arch exercises. [Subjects] The study recruited 11 healthy volunteers who were pain-free, had no history of foot or ankle surgery, and were able to maintain a standing posture. [Methods] The subjects performed short-foot and toe-spreading exercises while sitting and standing. [Results] The abductor hallucis muscle activation in the toe-spreading exercise was significantly greater when standing than in sitting, while that in the short-foot exercise did not differ significantly between the two postures. [Conclusion] The results of this study suggests that a weight bearing posture such as standing is the most effective method of increasing the EMG activity of abductor hallucis muscle in the toe-spreading exercise. PMID:25364132

Goo, Young-Mi; Heo, Hyo-Jin; An, Duk-Hyun

2014-01-01

37

In vivo kinematics of the ACL during weight-bearing knee flexion  

Microsoft Academic Search

No study has investigated the three-dimensional morphological changes of the anterior cruciate ligament (ACL) during functional activities in vivo. The purpose of this study was to analyze the elongation, rotation (twist), and orientation of the ACL during weight-bearing flexion in five human subjects using dual-orthogonal fluoroscopic images and MR image-based computer models. The ACL consistently decreased in length with flexion.

Guoan Li; Louis E. DeFrate; Harry E. Rubash; Thomas J. Gill

2005-01-01

38

Quadriceps Fatigue Alters Human Muscle Performance during a Novel Weight Bearing Task  

PubMed Central

Limited information is currently available regarding muscle synergistic patterns and triggered reflex responses during dynamic weight bearing activities in the presence of muscle fatigue. Purpose The purpose of this study was to examine the effects of quadriceps muscle fatigue on patterns of muscle activation and performance in response to sudden, unexpected perturbations during a weight-bearing task. Methods Motion of the knee was measured as subjects were asked to track a visual target as accurately as possible while performing a resisted single leg squat task. Random perturbations were delivered in 20% of the trials by unexpectedly releasing the resistance during the flexion phase of the exercise. Absolute and constant errors were calculated to evaluate target tracking performance. Quadriceps and hamstring muscle activity was recorded during both perturbed and unperturbed trials. Twelve healthy females were tested before and after completing a repetitive submaximal eccentric quadriceps fatigue protocol. A second group of 12 females served as controls. Unexpected perturbations elicited long latency responses characterized by facilitation of the quadriceps and inhibition of the hamstrings. Results Muscle fatigue increased the amplitude of the long latency response in vastus lateralis by 4.3% maximum voluntary isometric contraction (p=.004). Changes in tracking error occurred in response to perturbations after fatigue in spite of significantly increased quadriceps muscle activity, especially during the extension phase of the exercise. Conclusion Quadriceps muscle fatigue alters the patterns of coordinated muscle activity and may render subjects less able to cope with unexpected perturbations during weight bearing tasks. PMID:20164810

Ballantyne, Bryon T.; Shields, Richard K.

2010-01-01

39

Weight-Bearing Exercise Accuracy Influences Muscle Activation Strategies of the Knee  

PubMed Central

Purpose Dynamic stability of the knee joint is a research topic of increasing focus after ACL injury, stroke, and incomplete spinal cord injury. Since rehabilitation programs use functional weight-bearing tasks to improve neuromuscular control of the knee, it is important to understand the adaptability of muscle control strategies during weight-bearing exercise. The purpose of this study was to compare muscle activation patterns during a single leg squat (SLS) exercise performed before and after feedback-controlled training. Methods This was a cross-sectional comparative study. Fifteen young, healthy individuals performed the SLS exercise while tracking a sinusoidal target with flexion and extension of the knee. The SLS instrument provided bidirectional resistance that was normalized to body weight. Six trials of 10 repetitions of the SLSs were performed to quantify improved performance (learning). Electromyographic activity from five muscles that cross the knee was analyzed. Accuracy of performance was measured by calculating the error between the target and actual knee displacement. Results Reduction in error measurements verified that individuals increased the accuracy of performance in each trial and retained this improvement across trials (p < 0.05). Modulation in muscle activity as a result of learning was reflected mainly in the biceps femoris, rectus femoris, and vastus lateralis muscles. Conclusion Increased accuracy with the SLS exercise was accompanied by a decrease in coactivation of selected musculature around the knee. This study presents a novel approach to quantify the effect of performance on muscle synergistic activation patterns during weight-bearing exercise. Controlled strengthening, as defined in this study, emphasizes accuracy of performance in conjunction with principles of strength training and has implications to knee control. PMID:17419885

Madhavan, Sangeetha; Shields, Richard K.

2014-01-01

40

In vivo kinematics of the knee during weight bearing high flexion.  

PubMed

Achieving high flexion is an objective of contemporary total knee arthoplasty; however little is known on the knee biomechanics at high flexion under weight-bearing conditions. This study investigates the 6DOF kinematics and tibiofemoral cartilage contact biomechanics of the knee during weight-bearing flexion from full extension to maximal flexion. Eight knees from seven healthy subjects with no history of injuries or chronic pain were recruited. The knees were MRI scanned to create 3D models of the tibia and femur, including their articular cartilage surfaces. The subjects were then imaged using a dual fluoroscopic image system while performing a weight-bearing quasi-static single-legged lunge from full extension to maximal flexion. The 6DOF kinematics and the articular cartilage contact locations were measured along the flexion path of the knee. The result indicated that the internal tibial rotation increased sharply at low flexion angles (full extension to 30°), maintained a small variation in the middle range of flexion (30-120°, and then sharply increased again at high flexion angles (120° to maximal flexion). The contact point moved similarly in the medial and lateral compartments before 120° of flexion, but less on the medial compartment at high flexion angles. The results indicated that the knee motion could not be described using one character in the entire range of flexion, especially in high flexion. The knee kinematic data in the entire range of flexion of the knee could be instrumental for designing new knee prostheses to achieve physical high flexion and improving rehabilitation protocols after knee injuries. PMID:23591448

Qi, Wei; Hosseini, Ali; Tsai, Tsung-Yuan; Li, Jing-Sheng; Rubash, Harry E; Li, Guoan

2013-05-31

41

Magnetic resonance imaging evaluation of weight-bearing subchondral trabecular bone in the knee  

Microsoft Academic Search

Objective  Changes in weight-bearing subchondral bone are central to osteoarthritis (OA) pathophysiology. Using MR, knee trabecular bone\\u000a is typically assessed in the axial plane, however partial volume artifacts limit the utility of MR methods for femorotibial\\u000a compartment subchondral bone analysis. Oblique-coronal acquisitions may enable direct visualization and quantification of\\u000a the expected increases in femorotibial subchondral trabecular bone.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  MR acquisition parameters were

Erika Schneider; Grace H. Lo; Gretchen Sloane; Lynn Fanella; David J. Hunter; Charles B. Eaton; Timothy E. McAlindon

2011-01-01

42

Bears, Bears, Bears!  

NSDL National Science Digital Library

What are some things you learned about bears? Use these websites to find out about bears: Parts of a Bear Polar Bears Real Story of the Three Bears The truth about bears Brown Bears Now fill in your chart! Bear Fact Sheet Listen to your teacher for further instruction on completing a book about bears! ...

Ms.beason

2011-04-16

43

Alterations of collagen matrix in weight-bearing bones during skeletal unloading  

NASA Technical Reports Server (NTRS)

Skeletal unloading induces loss of bone mineral density in weight-bearing bones. The objectives of this study were to characterize the post-translational modifications of collagen of weight-bearing bones subjected to hindlimb unloading for 8 weeks. In unloaded bones, tibiae and femurs, while the overall amino acid composition was essentially identical in the unloaded and control tibiae and femurs, the collagen cross-link profile showed significant differences. Two major reducible cross-links (analyzed as dihydroxylysinonorleucine and hydroxylysinonorleucine) were increased in the unloaded bones. In addition, the ratios of the former to the latter as well as pyridinoline to deoxypyridinoline were significantly decreased in the unloaded bones indicating a difference in the extent of lysine hydroxylation at the cross-linking sites between these two groups. These results indicate that upon skeletal unloading the relative pool of newly synthesized collagen is increased and it is post-translationally altered. The alteration could be associated with impaired osteoblastic differentiation induced by skeletal unloading that results in a mineralization defect.

Shiiba, M.; Arnaud, S. B.; Tanzawa, H.; Uzawa, K.; Yamauchi, M.

2001-01-01

44

Effects of immobilization on rat hind limb muscles under non-weight-bearing conditions  

NASA Technical Reports Server (NTRS)

The effect of stretched and unstretched immobilization of a hind limb on the concentration and the metabolism of proteins in the hind-limb muscles of rats was investigated. The animals were divided into three groups: (1) weight-bearing controls, (2) tail-cast-suspended, and (3) suspended, with one hind limb immobilized with the ankle in dorsiflexion (30-40 deg angle) and the other freely moving. It was found that unloading the hind limbs for 6 days by tail cast suspension caused soleus to atrophy and reduced growth of the gastrocnemius and plantaris muscles; unloading resulted in a higher degradation rate and lower synthesis rate in both in vitro and in vivo. Chronic stretch of the unloaded soleus not only prevented its atrophy but led to significant hypertrophy, relative to weight-bearing controls, with increases in both the sarcoplasmic and myofibrillar protein fractions. Immobilizing one ankle in dorsiflexion prevented the inhibition of growth in the plantaris and gastrocnemius muscles due to unloading.

Jaspers, Stephen R.; Fagan, Julie M.; Satarug, Soisungwan; Cook, Paul H.; Tischler, Marc E.

1988-01-01

45

Non-weight-bearing neural control of a powered transfemoral prosthesis  

PubMed Central

Lower limb prostheses have traditionally been mechanically passive devices without electronic control systems. Microprocessor-controlled passive and powered devices have recently received much interest from the clinical and research communities. The control systems for these devices typically use finite-state controllers to interpret data measured from mechanical sensors embedded within the prosthesis. In this paper we investigated a control system that relied on information extracted from myoelectric signals to control a lower limb prosthesis while amputee patients were seated. Sagittal plane motions of the knee and ankle can be accurately (>90%) recognized and controlled in both a virtual environment and on an actuated transfemoral prosthesis using only myoelectric signals measured from nine residual thigh muscles. Patients also demonstrated accurate (~90%) control of both the femoral and tibial rotation degrees of freedom within the virtual environment. A channel subset investigation was completed and the results showed that only five residual thigh muscles are required to achieve accurate control. This research is the first step in our long-term goal of implementing myoelectric control of lower limb prostheses during both weight-bearing and non-weight-bearing activities for individuals with transfemoral amputation. PMID:23782953

2013-01-01

46

Orthotic devices and gait in polio patients.  

PubMed

Polio survivors are aging and facing multiple pathologies. With age, walking becomes more difficult, partly due to locomotor deficits but also as a result of weight gain, osteoarticular degeneration, pain, cardiorespiratory problems or even post polio syndrome (PPS). These additional complications increase the risk of falls in this population where the risk of fractures is already quite high. The key joint is the knee. The muscles stabilizing this joint are often weak and patients develop compensatory gait strategies, which could be harmful to the locomotor system at medium or long term. Classically, knee recurvatum is used to lock the knee during weight bearing; however, if it exceeds 10 degrees , the knee becomes unstable and walking is unsafe. Thus, regular medical monitoring is necessary. Orthoses play an important role in the therapeutic care of polio survivors. The aim is usually to secure the knee, preventing excessive recurvatum while respecting the patient's own gait. Orthoses must be light and pressure-free if they are to be tolerated and therefore effective. Other joints present fewer problems and orthoses are rarely indicated just for them. The main issue lies in the prior evaluation of treatments' impact. Some deformities may be helpful for the patients' gait and, therefore, corrections may worsen their gait, especially if a realignment of segments is attempted. It is therefore essential to carefully pre-assess any change brought to the orthoses as well as proper indications for corrective surgery. In addition, it is essential for the patient to be monitored by a specialized team. PMID:20022835

Genêt, F; Schnitzler, A; Mathieu, S; Autret, K; Théfenne, L; Dizien, O; Maldjian, A

2010-02-01

47

Prospective, Blinded, Randomized Crossover Study of Gait Rehabilitation in Stroke Patients Using the Lokomat Gait Orthosis  

Microsoft Academic Search

Objective. Treadmill training with partial body weight support has been suggested as a useful strategy for gait rehabilitation after stroke. This prospective, blinded, randomized controlled study of gait retraining tested the feasibility and potential effi- cacy of using an electromechanical-driven gait orthosis (Lokomat) for treadmill training. Methods. Sixteen stroke patients, mostly within 3 months after onset, were random- ized into

Andreas Mayr; Markus Kofler; Ellen Quirbach; Heinz Matzak; Katrin Fröhlich; Leopold Saltuari

48

Soleus Fiber Force and Maximal Shortening Velocity After Non-Weight Bearing with Intermittent Activity  

NASA Technical Reports Server (NTRS)

This study examined the effectiveness of intermittent weight bearing (IWB) as a countermeasure to non-weight-bearing (NWB)-induced alterations in soleus type 1 fiber force (in mN), tension (P(sub o); force per fiber cross-sectional area in kN/sq m), and maximal unloaded shortening velocity (V(sub o), in fiber lengths/s). Adult rats were assigned to one of the following groups: normal weight bearing (WB), 14 days of hindlimb NWB (NWB group), and 14 days of hindlimb NWB with IWB treatments (IWB group). The IWB treatment consisted of four 10-min periods of standing WB each day. Single, chemically permeabilized soleus fiber segments were mounted between a force transducer and position motor and were studied at maximal Ca(2+) activation, after which type 1 fiber myosin heavy-chain composition was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. NWB resulted in a loss in relative soleus mass (-45%), with type 1 fibers displaying reductions in diameter (-28%) and peak isometric force (-55%) and an increase in V(sub o) (+33%). In addition, NWB induced a 16% reduction in type 1 fiber P., a 41% reduction in type 1 fiber peak elastic modulus [E(sub o), defined as ((delta)force/(delta)length x (fiber length/fiber cross-sectional area] and a significant increase in the P(sub o)/E(sub o) ratio. In contrast to NWB, IWB reduced the loss of relative soleus mass (by 22%) and attenuated alterations in type 1 fiber diameter (by 36%), peak force (by 29%), and V(sub o)(by 48%) but had no significant effect on P(sub o), E(sub o) or P(sub o)/E(sub o). These results indicate that a modest restoration of WB activity during 14 days of NWB is sufficient to attenuate type 1 fiber atrophy and to partially restore type 1 peak isometric force and V(sub o) to WB levels. However, the NWB-induced reductions in P(sub o) and E(sub o) which we hypothesize to be due to a decline in the number and stiffness of cross bridges, respectively, are considerably less responsive to this countermeasure treatment.

Widrick, Jeffrey J.; Bangart, Jill J.; Karhanek, Miloslav; Fitts, Robert H.

1996-01-01

49

The effects of weight bearing yoga training on the bone resorption markers of the postmenopausal women.  

PubMed

This study was a preliminary report to investigate the effects of the weight bearing yoga training on both bone resorption marker and the quality of life of the postmenopausal women. The samples were recruited by the purposive sampling from the female Chulalongkorn University staff aged between 50-60 years. The subjects were divided into two groups: experimental group and control group. The baseline demographic data, the bone resorption marker (beta-CrossLaps), the bone formation marker (P1NP) and quality of Life (SF-36) data were collected. The experimental group attended the 12-week weight-bearing yoga training 3 days a week, 50 minutes a day while the control group lived their normal lives. After 12th week, the data collections were repeated in both groups. The experimental group (19 subjects, the mean age 54.320 yrs) and the control group (14 subjects, the mean age 54.430 yrs) were recruited. The mean ultrasound BMD of both heels in both groups showed no osteopenia or osteoporosis. After the 12-week training, the mean bone resorption marker (beta-CrossLaps) of the experimental group reduced from 0.464 to 0.339 ng/ml (-26.939%) whereas the control group reduced from 0.389 to 0.386 ng/ml (-0.771%). There was a significant difference (p < 0.05). The mean of the bone formation markers (PINP) in the experimental group reduced from 55.393 to 42.401 ng/ml (-23.454%) and the bone formation markers (PINP) in the control group reduced from 61.903 to 44.832 ng/ml (-27.577%). In the area of the life quality measurement of both groups, the data obtained from the medical outcomes study short-form survey (SF-36) showed that there were significant differences at 0.05 levels for the physical functioning, bodily pain, general health, and vitality. The variance of percentage change value of the experimental group increased to +25.299, +16.565, +15.309, and +21.056. The variance of percentage change value of the control group increased to +12.946, -1.221, -9.303 and +2.291. The weigh-bearing yoga training had a positive effect on bone by slowing down bone resorption which was a very essential indicator for human health because it reduced the osteoporosis risks in the postmenopausal women. Additionally, yoga training promoted better quality of life. PMID:19891384

Phoosuwan, Manop; Kritpet, Thanomwong; Yuktanandana, Pongsak

2009-09-01

50

Gait disorders.  

PubMed

Gait disorders are frequently accompanied by loss of balance and falls, and are a common cause of disability, particularly among the elderly. In many cases the cause is multifactorial, involving both neurologic and nonneurologic systems. Physical therapy and training, coupled with pharmacologic and surgical therapy, can usually provide some improvement in ambulation, which translates into better quality of life. More research is needed on the mechanisms of gait and its disorders as well as on symptomatic therapies. Better understanding of the pathophysiology of gait disorders should lead to more specific, pathogenesis-targeted therapies. PMID:25432732

Jankovic, Joseph

2015-02-01

51

Effects of early weight bearing on the functional recovery of ambulatory children with cerebral palsy after bilateral proximal femoral osteotomy.  

PubMed

This study evaluates the effects of early versus delayed weight bearing on the functional recovery of ambulatory children with cerebral palsy (CP) after they have undergone proximal femoral osteotomies (PFOs). We retrospectively reviewed the cases of 25 ambulatory children with CP who underwent PFO to correct excessive hip internal rotation and intoeing. Thirteen children were permitted to weight-bear as tolerated (WBAT) immediately after surgery, and 12 were placed on non-weight bearing restrictions for 3 to 7 weeks (mean +/- SD, 30 +/- 6.7 days). There were no major complications. The children in the WBAT group initiated standing 26 days sooner and returned to baseline walking almost 4 months sooner than those on non-weight bearing restrictions. Pain at 8 days postoperatively was significantly less for the WBAT group, but pain at the time of initial standing and walking was not significantly different between groups. In conclusion, early mobilization after PFOs in children with CP is safe, with reduced recovery time, and with decreased pain. PMID:17717468

Schaefer, Megan K; McCarthy, James J; Josephic, Kyle

2007-09-01

52

Hormonal, hypothalamic and striatal responses to reduced body weight gain are attenuated in anorectic rats bearing small tumors  

Microsoft Academic Search

Lack of compensatory or even reduced food intake is frequently observed in weight-losing cancer patients and contributes to increased morbidity and mortality. Our previous work has shown increased transcription factor expression in the hypothalamus and ventral striatum of anorectic rats bearing small tumors. mRNA expression of molecules known to be involved in pathways regulating appetite in these structures was therefore

Line Pourtau; Susan Leemburg; Pascale Roux; Thierry Leste-Lasserre; Patricia Costaglioli; Bertrand Garbay; Guillaume Drutel; Jan Pieter Konsman

2011-01-01

53

Non-weight bearing-induced muscle weakness: the role of myosin quantity and quality in MHC type II fibers  

PubMed Central

We tested the hypothesis that non-weight bearing-induced muscle weakness (i.e., specific force) results from decreases in myosin protein quantity (i.e., myosin content per half-sarcomere and the ratio of myosin to actin) and quality (i.e., force per half-sarcomere and population of myosin heads in the strong-binding state during muscle contraction) in single myosin heavy chain (MHC) type II fibers. Fisher-344 rats were assigned to weight-bearing control (Con) or non-weight bearing (NWB). The NWB rats were hindlimb unloaded for 2 wk. Diameter, force, and MHC content were determined in permeabilized single fibers from the semimembranosus muscle. MHC isoform and the ratio of MHC to actin in each fiber were determined by gel electrophoresis and silver staining techniques. The structural distribution of myosin from spin-labeled fiber bundles during maximal isometric contraction was evaluated using electron paramagnetic resonance spectroscopy. Specific force (peak force per cross-sectional area) in MHC type IIB and IIXB fibers from NWB was significantly reduced by 38% and 18%, respectively. MHC content per half-sarcomere was significantly reduced by 21%. Two weeks of hindlimb unloading resulted in a reduced force per half-sarcomere of 52% and fraction of myosin strong-binding during contraction of 34%. The results suggest that reduced myosin and actin content (quantity) and myosin quality concomitantly contribute to non-weight bearing-related muscle weakness. PMID:24829495

Kim, Jong-Hee

2014-01-01

54

Comparison of dermatoscopic images of acral lentiginous melanoma and acral melanocytic nevus occurring on body weight-bearing areas  

PubMed Central

Background: Because body weight-bearing produces a shift in the horny layer, acral melanocytic nevus on the body weight-bearing area of the sole showed a regular fibrillar pattern (FP) due to slanting of the melanin columns in the horny layer. On the other hand, acral lentiginous melanoma (ALM) on the body weight-bearing area of the sole tended to show irregular fibrillar pattern showing rather structureless pigmentation instead of a parallel ridge pattern, which is due to the shift of the horny layer. Objective: To elucidate the subtle difference between the regular FP of nevus and irregular FP in ALM. Methods: In this study, the dermatoscopic features of five cases of ALM and five cases of acral melanocytic nevus on the weight-bearing area of the sole were compared. Results: All the cases with nevi showed regular FP showing regular distribution of fibrils, whereas all the melanomas showed irregular distribution of fibrils and colors. Fibrils in nevi tended to be clear at the furrows and dim at the ridges. White fibrils corresponding to the eccrine ducts in the horny layer were more often present on the ridges in ALM, which showed negative FP. Conclusion: Differentiating between the regular and irregular FP, including negative FP, might be helpful for the discrimination of melanoma from nevus. PMID:25396085

Watanabe, Soko; Sawada, Mizuki; Ishizaki, Sumiko; Kobayashi, Ken; Tanaka, Masaru

2014-01-01

55

Movement Accuracy Changes Muscle-Activation Strategies in Female Subjects During a Novel Single-Leg Weight-Bearing Task  

PubMed Central

Objective Understanding of how female subjects learn to move accurately during a resisted weight-bearing task is limited. The purpose of this study was to examine the muscle activation patterns used by female subjects in learning a novel single-leg squat (SLS) task under visual and nonvisual conditions. Design Prospective training study. Setting University research setting. Participants Ten healthy young female participants. Intervention Subjects tracked a sinusoidal target (knee displacement) during a resisted SLS exercise during the course of 4 days, under eyes open (EO) and eyes closed (EC) conditions with the use of a custom-designed weight-bearing exercise device. Main Outcome Measurement The accuracy of performance in tracking the target and electromyographic activity (EMG) of 5 muscles around the knee were monitored. Results Subjects improved their accuracy of performance by day 2 (40% decrease in error) and retained the accuracy on day 4. Error during the EC condition was 3 times greater than EO condition. Quadriceps-to-hamstrings coactivation ratio increased with the improved accuracy from the learning. Absence of visual feedback was accompanied by a decrease in the quadriceps-to-hamstrings coactivation ratio for this task. Conclusion The muscle synergistic activity around the knee changes as the accuracy of the task improves during a resisted weight-bearing task. This activation pattern represents a feed forward control plan that the central nervous system adopted to optimize accurate weight-bearing knee displacement. Rehabilitation specialists should consider manipulating the visual feedback and accuracy of performance when developing weight-bearing rehabilitation training protocols to improve neuromuscular control in female patients. PMID:19627914

Madhavan, Sangeetha; Shields, Richard K.

2009-01-01

56

Replacement arthroplasty in the weight-bearing shoulder of paraplegic patients.  

PubMed

We review the early results of shoulder arthroplasty in the weight-bearing shoulder of long-term paraplegic patients. We have been unable to find previously published results of this subgroup of shoulder arthroplasty patients in the literature. Five paraplegic, female patients who had undergone shoulder arthroplasty were analyzed. All patients had been prospectively assessed with the American Shoulder and Elbow Surgeons (ASES) function score and the Constant score. The mean age at the time of surgery was 70 years. Three shoulders had full-thickness rotator cuff tears, and two were repaired at the time of shoulder arthroplasty. The mean preoperative Constant score was 30 out of 100, improving to 52 out of 100 at a mean follow-up of 30 months (range, 24-36 months). The mean preoperative ASES function score was 28 out of 55, improving to 37 out of 55. One patient was pain-free after surgery, and the mean postoperative pain score was 10 out of 15. There were no features of progressive radiolucency around the glenoid or the humeral components at last review apart from one case in which glenoid implant migration occurred. In view of the satisfactory improvement in terms of pain, mobility, and independence, we believe that it is reasonable to continue to offer this procedure to this subgroup of patients. We will, however, remain vigilant with regard to any further complications arising in these prostheses in the medium to long term as a result of increased loading. PMID:15220875

Garreau De Loubresse, C; Norton, M R; Piriou, P; Walch, G

2004-01-01

57

Benign acute childhood myositis--a rare cause of abnormal gait.  

PubMed

Benign acute childhood myositis is a rare postviral myositis seen in school-aged children after a common upper respiratory infection (URI), most commonly caused by influenza [J Microbiol Immunol Infect 2004;37:95-98]. Predominantly seen in boys, this condition causes bilateral calf tenderness and pain with ambulation, often presenting as a refusal to bear weight. To avoid activation within the gastroc-soleus complex, the child will frequently compensate with a “Frankenstein gait,” described as a stiff-legged posture with shuffling gait [CMAJ 2009;181:711-713]. The child may also walk on his toes or refuse to walk at all. This refusal to bear weight can be alarming to both providers and parents, resulting in extensive workups. We present the case of a 5-year-old boy who presented to the emergency department with a chief complaint of leg pain and refusal to walk. Further history revealed a resolved URI approximately 5 days prior. He was noted to have an elevated creatinine kinase with no evidence of renal insufficiency. He had no progression or complications, and his symptoms resolved spontaneously with minimal supportive treatment. Benign acute childhood myositis should be considered within the broad differential that surrounds a limping child or one who refuses to bear weight. Having insight into the condition with its characteristic gait abnormalities and associated URI history can often prevent extensive workups and be treated supportively in the outpatient setting. PMID:24126025

Hall, Gregory; Schranz, Craig I

2014-02-01

58

Balance asymmetry in Parkinson's disease and its contribution to freezing of gait.  

PubMed

Balance control (the ability to maintain an upright posture) is asymmetrically controlled in a proportion of patients with Parkinson's disease. Gait asymmetries have been linked to the pathophysiology of freezing of gait. We speculate that asymmetries in balance could contribute to freezing by a) hampering the unloading of the stepping leg and/or b) leading to a preferred stance leg during gait, which then results in asymmetric gait. To investigate this, we examined the relationship between balance control and weight-bearing asymmetries and freezing. We included 20 human patients with Parkinson (tested OFF medication; nine freezers) and nine healthy controls. Balance was perturbed in the sagittal plane, using continuous multi-sine perturbations, applied by a motion platform and by a force at the sacrum. Applying closed-loop system identification techniques, relating the body sway angle to the joint torques of each leg separately, determined the relative contribution of each ankle and hip joint to the total amount of joint torque. We also calculated weight-bearing asymmetries. We determined the 99-percent confidence interval of weight-bearing and balance-control asymmetry using the responses of the healthy controls. Freezers did not have larger asymmetries in weight bearing (p?=?0.85) nor more asymmetrical balance control compared to non-freezers (p?=?0.25). The healthy linear one-to-one relationship between weight bearing and balance control was significantly different for freezers and non-freezers (p?=?0.01). Specifically, non-freezers had a significant relationship between weight bearing and balance control (p?=?0.02), whereas this relation was not significant for freezers (p?=?0.15). Balance control is asymmetrical in most patients (about 75 percent) with Parkinson's disease, but this asymmetry is not related to freezing. The relationship between weight bearing and balance control seems to be less pronounced in freezers, compared to healthy controls and non-freezers. However, this relationship should be investigated further in larger groups of patients. PMID:25032994

Boonstra, Tjitske A; van Vugt, Jeroen P P; van der Kooij, Herman; Bloem, Bastiaan R

2014-01-01

59

A new method to assess weight-bearing distribution after central nervous system lesions in rats.  

PubMed

The aim of the present study is to assess the relevance of weight-bearing distribution (DWB) measurement in freely moving rats after stroke and thoracic spinal cord injuries. Animals were divided in 2 experiments: (1) The middle cerebral artery occlusion-reperfusion (MCAO-r) experiment containing the MCAO group in which focal brain ischaemia was induced by transient MCA occlusion and (2) the thoracic hemisection experiment containing the TH group in which a spinal cord hemisection was performed at the T10 level. A Control and respective Sham groups were also included in each experiment. Not only the pressure exerted by each paw was measured but also different ratios such as: (1) the sum of the right and the left forepaws was normalized by the sum of the right and the left hindpaws (F/H), (2) the left forepaw was normalized by the right forepaw (LF/RF), (3) the left hindpaw was normalized by the right hindpaw (LH/RH). Additionally, the times spent on 3 paws and on 4 paws were measured. Only the time spent on 4 paws was shorter in the MCAO group than in the Control (p<0.001) and in the Sham (p<0.01) groups. The LH/RH ratio of the TH group at the 1st week was lower (p<0.01) than the pre-surgical value. Moreover, its F/H ratio was superior (p<0.001) to the ones of the Control and the Sham groups. Our study indicates that DWB should be more frequently used to evaluate both the severity of central nervous system traumas and the effectiveness of pharmacological and/or rehabilitation strategies. PMID:24200548

Pertici, Vincent; Pin-Barre, Caroline; Felix, Marie-Solenne; Laurin, Jérôme; Brisswalter, Jeanick; Decherchi, Patrick

2014-02-01

60

Effect of recovery from muscle strength imbalance in lower limb using four point weight bearing reduction system.  

PubMed

This study was performed to assess the improvement of muscle strength imbalance in the lower limbs using a four point weight bearing reduction system with a two-belt treadmill. Participants, each having differences in muscle function of the left and right legs of over 20%, were divided into two groups of ten. The participants were involved in experiments progressing 40 minutes per day, 3 days per week, during a period of 4 weeks. The maximal peak torque and average power were measured for testing joint torque in the hip, knee and ankle. The results showed the improvement of muscle imbalance as assessed by the maximal muscle strength was the most effective in the hip joint, while the improvement of muscular reaction was the most effective in the knee joint. We suggest that the method of weight bearing reduction could be sufficient to reduce muscle imbalance in the lower limbs. PMID:25226948

Yu, Chang Ho; Kang, Seung Rok; Jeong, Ho Choon; Kim, Kyung; Kwon, Tae Kyu

2014-01-01

61

Biofeedback rehabilitation of posture and weight-bearing distribution in stroke: a center of foot pressure analysis  

PubMed Central

Summary Weight bearing on the paretic lower extremity and transfer of weight from one lower extremity to the other are important goals of stroke rehabilitation. Improvements in these limb loading and weight transfer abilities have been shown to relate to improved performance of many functional activities. Unfortunately, valid and practical clinical measures of paretic lower extremity loading and weight transfer have not been identified. The purpose of this study was to quantitatively assess, through center of foot pressure (CoP) analysis of quiet upright stance control, recovery of paretic limb loading as a measure of weight transfer in early stroke subjects, testing the effectiveness of a targeted rehabilitation intervention based on audio-visual biofeedback. Thirty-seven adults with lower extremity motor impairment following unilateral, non-cerebellar stroke, were tested twice, at an interval of at least one month post stroke and following rehabilitation intervention aimed at correcting their asymmetrical weight bearing. The intervention was performed with (Study Group, SG) or without (Control Group, CG) a postural audio-visual biofeedback approach. Indices of postural stability and of balance control asymmetry were estimated by acquiring the movements of the CoP during quiet upright stance condition with or without visual input (eyes open, EO and eyes closed, EC). Clinical scales were also administered. Both the CG and the SG subjects showed improved control in upright stance posture as documented by significant improvements in the scale scores and indices of stability during both the EO and the EC condition. Only the SG showed a significantly reduced CoP index of asymmetry. The CoP index of asymmetry, correlating with clinical motor scales, is a valid measure of paretic limb loading during stroke recovery. Postural audio-visual biofeedback represented the more effective approach for reducing weight loading asymmetry of the lower limbs in stroke. PMID:25306123

De Nunzio, Alessandro Marco; Zucchella, Chiara; Spicciato, Francesca; Tortola, Paolo; Vecchione, Carmine; Pierelli, Francesco; Bartolo, Michelangelo

2014-01-01

62

Reducing Risk of Falling in Older People Discharged From Hospital: A Randomized Controlled Trial Comparing Seated Exercises, Weight-Bearing Exercises, and Social Visits  

Microsoft Academic Search

Vogler CM, Sherrington C, Ogle SJ, Lord SR. Reducing risk of falling in older people discharged from hospital: a randomized controlled trial comparing seated exercises, weight-bearing exercises, and social visits.

Constance M. Vogler; Catherine Sherrington; Susan J. Ogle; Stephen R. Lord

2009-01-01

63

Glutamine depletion and increased gut permeability in nonanorectic, non-weight-losing tumor-bearing rats  

Microsoft Academic Search

BACKGROUND & AIMS: Glutamine is an essential amino acid for rapidly dividing cells such as enterocytes. The progress of cancer is associated with a decrease of arterial and muscle glutamine concentrations. The aim of this study was to test whether increasing tumor loads affect gut intracellular glutamine handling, protein turnover, and gut absorptive and barrier function. METHODS: Methylcholantrene-induced tumor-bearing rats

I De Blaauw; NE Deutz; RR van der Hulst; MF von Meyenfeldt

1997-01-01

64

Study of the polycarbonate-urethane/metal contact in different positions during gait cycle.  

PubMed

Nowadays, a growing number of young and more active patients receive hip replacement. More strenuous activities in such patients involve higher friction and wear rates, with friction on the bearing surface being crucial to ensure arthroplasty survival in the long term. Over the last years, the polycarbonate-urethane has offered a feasible alternative to conventional bearings. A finite element model of a healthy hip joint was developed and adjusted to three gait phases (heel strike, mid-stance, and toe-off), serving as a benchmark for the assessment of the results of joint replacement model. Three equivalent models were made with the polycarbonate-urethane Tribofit system implanted, one for each of the three gait phases, after reproducing a virtual surgery over the respective healthy models. Standard body-weight loads were considered: 230% body-weight toe-off, 275% body-weight mid-stance, and 350% body-weight heel strike. Contact pressures were obtained for the different models. When comparing the results corresponding to the healthy model to polycarbonate-urethane joint, contact areas are similar and so contact pressures are within a narrower value range. In conclusion, polycarbonate-urethane characteristics are similar to those of the joint cartilage. So, it is a favorable alternative to traditional bearing surfaces in total hip arthroplasty, especially in young patients. PMID:25247180

Gabarre, Sergio; Herrera, Antonio; Mateo, Jesús; Ibarz, Elena; Lobo-Escolar, Antonio; Gracia, Luis

2014-01-01

65

Study of the Polycarbonate-Urethane/Metal Contact in Different Positions during Gait Cycle  

PubMed Central

Nowadays, a growing number of young and more active patients receive hip replacement. More strenuous activities in such patients involve higher friction and wear rates, with friction on the bearing surface being crucial to ensure arthroplasty survival in the long term. Over the last years, the polycarbonate-urethane has offered a feasible alternative to conventional bearings. A finite element model of a healthy hip joint was developed and adjusted to three gait phases (heel strike, mid-stance, and toe-off), serving as a benchmark for the assessment of the results of joint replacement model. Three equivalent models were made with the polycarbonate-urethane Tribofit system implanted, one for each of the three gait phases, after reproducing a virtual surgery over the respective healthy models. Standard body-weight loads were considered: 230% body-weight toe-off, 275% body-weight mid-stance, and 350% body-weight heel strike. Contact pressures were obtained for the different models. When comparing the results corresponding to the healthy model to polycarbonate-urethane joint, contact areas are similar and so contact pressures are within a narrower value range. In conclusion, polycarbonate-urethane characteristics are similar to those of the joint cartilage. So, it is a favorable alternative to traditional bearing surfaces in total hip arthroplasty, especially in young patients. PMID:25247180

Herrera, Antonio; Mateo, Jesús; Lobo-Escolar, Antonio

2014-01-01

66

Asymmetry of Anticipatory Postural Adjustment During Gait Initiation  

PubMed Central

The purpose of this study was to investigate the asymmetry of anticipatory postural adjustment (APA) during gait initiation and to determine whether the process of choosing the initial swing leg affects APA during gait initiation. The participants initiated gait with the leg indicated by a start tone or initiated gait with the leg spontaneously chosen. The dependent variables of APA were not significantly different among the condition of initiating gait with the preferred leg indicated by the start tone, the condition of initiating gait with the non-preferred leg indicated by the start tone, and the condition of initiating gait with the leg spontaneously chosen. These findings fail to support the view that the process of choosing the initial swing leg affects APA during gait initiation. The lateral displacement of the center of pressure in the period in which shifting the center of pressure to the initial swing phase before initiating gait with the left leg indicated by the external cue was significantly larger than that when initiating gait with the right leg indicated by the external cue, and significantly larger than that when initiating gait with the leg spontaneously chosen. Weight shift to the initial swing side during APA during gait initiation was found to be asymmetrical when choosing the leg in response to an external cue. PMID:25414735

Hiraoka, Koichi; Hatanaka, Ryota; Nikaido, Yasutaka; Jono, Yasutomo; Nomura, Yoshifumi; Tani, Keisuke; Chujo, Yuta

2014-01-01

67

Effect of spaceflight on the non-weight-bearing bones of rat skeleton  

NASA Technical Reports Server (NTRS)

The effects of weightlessness on the integrated growth and remodeling of nonweight-bearing bones (the mandibles, teeth, and ribs) were studied. Rats prelabeled with tetracycline to mark the surfaces of bone and tooth formation were subjected to spaceflight conditions for 18.5 days, followed by further injections of tetracycline on days 6 and 29 postflight.Results show that spaceflight conditions did not alter the rate of periosteal bone formation in the ribs and regions of the mandibles covered by masticatory muscles, although bone formation-calcification rates were found to be impaired at those sites in the jaw that had no contiguous muscle (molar region). The remodeling activity on the alveolar bone around the buccal roots of the molar teeth was found to be significantly reduced. While total Ca, P, and hydroxyproline concentrations in the jaws, incisors, and ribs were normal after spaceflight, it was determined that weightless conditions caused a delay in the maturation of bone mineral and matrix in the jaws. These anomalies were found to be corrected by 29 days postflight. These results indicate that most of the nonweight-bearing bones of the rat skeleton are at risk to the effects of weightlessness.

Simmons, D. J.; Russell, J. E.; Winter, F.; Tran Van, P.; Vignery, A.; Baron, R.; Rosenberg, G. D.; Walker, W. V.

1983-01-01

68

Variation in percentage weight bearing with changes in standing posture during water immersion: implication for clinical practice  

PubMed Central

Background The degree of weightlessness during water immersion is usually estimated through percentage weight bearing (PWB). However, variations in PWB in different standing postures have not been documented. The study was designed to investigate the PWB of apparently healthy individuals in four standing postures at the anterior superior iliac spine level of immersion. Methods One hundred and ninety-three consenting undergraduates were purposively enlisted in this study. Participants’ body weight (BW) was measured on land as well as in Erect Standing (ES), Grasp-Inclined-Prone-Standing (GIPS), Half-Grasp-Inclined-Towards-Side Standing (HGITSS) and Inclined-Standing with Head Support (ISHS) postures in hydro pool, using a specially designed water-proof weighing scale. PWB was calculated by dividing BW in water by BW on land and multiplying by 100. Data were analyzed using mean, standard deviation and ANOVA at ??=?0.05. Results The mean age and BW (on land) of the participants were 22.4 years and 60.7 kg respectively. Participants’ PWB were significantly different (p??0.05). Conclusion Changes in standing posture have significant effect on PWB in hydro pool. The finding has implication for partial weight bearing exercises in hydro pool. PMID:25091034

2014-01-01

69

Orientation of the first metatarsal base wedge osteotomy: perpendicular to the metatarsal versus weight-bearing surface.  

PubMed

Changes have been proposed in the orientation of the first metatarsal base closing abductory wedge osteotomy based on sound theoretical reasoning. The newer proposed method, utilizing an orientation of the osteotomy perpendicular to the weight-bearing surface, produces only pure transverse plane motion and no loss of ground contact by hinge axis mechanisms. In contrast, the traditional orientation of the osteotomy, perpendicular to the long axis of the metatarsal, produces extraneous frontal plane motion that results in loss of ground contact as the osteotomy site is closed. The presented study formulates a mathematical model to calculate the amount of loss of ground contact produced by the traditional osteotomy orientation. The values obtained from 168 calculations suggest far less clinical significance to the change than has been implied or stated previously. PMID:3225387

Palladino, S J

1988-01-01

70

Gait Analysis for Classification  

E-print Network

This thesis describes a representation of gait appearance for the purpose of person identification and classification. This gait representation is based on simple localized image features such as moments extracted from ...

Lee, Lily

2003-06-26

71

Gait analysis for classification  

E-print Network

This thesis describes a representation of gait appearance for the purpose of person identification and classification. This gait representation is based on simple localized image features such as moments extracted from ...

Lee, Lily, 1971-

2002-01-01

72

Slow gait in MCI is associated with ventricular enlargement: results from the Gait and Brain Study.  

PubMed

Slow gait is ubiquitous among older adults and predicts cognitive decline and progression to dementia. Age-related structural brain changes could be responsible for abnormal gait. The purpose of this study was to determine whether brain lateral ventricle volume, a measure of brain atrophy, was associated with gait velocity among older adults with mild cognitive impairment (MCI), while considering the effects of age and brain vascular burden. Twenty community-dwellers with MCI, free of hydrocephalus, aged 76 years (69/80) [median (25th/75th percentile)] (35 % female) from the 'Gait and Brain Study' were included in this analysis. Quantitative gait performance was measured while steady-state walking at self-selected pace with a 6-m electronic portable walkway (GAITRite). Brain ventricle volume was quantified using semi-automated software from three-dimensional T1-weighted magnetic resonance imaging. Age, white matter hyperintensity burden and Mini-Mental State Examination score were used as potential confounders. Median gait velocity was 118.7 cm/s (104.4/131.3). Median brain ventricle volume was 39.9 mL (30.0/46.6) with the left ventricle being slightly larger than the right (P = 0.052). Brain ventricle volume was inversely associated with gait velocity (adjusted ? = -0.63, P = 0.046). Volume of both the ventricular main bodies and the temporal horns correlated inversely with gait velocity (respectively, P = 0.009, P = 0.008). Left ventricle volume correlated with decreased gait velocity (P = 0.002) while right ventricle did not (P = 0.068). Slower gait velocity was associated with larger brain ventricle volume in our sample of people with MCI independent of age, cerebrovascular burden and cognitive worsening. This result may help elucidate the trajectories of cognitive and gait declines in people with MCI. PMID:23196981

Annweiler, C; Beauchet, O; Bartha, R; Montero-Odasso, M

2013-07-01

73

Do external stimuli impact the gait of children with idiopathic toe walking? A study protocol for a within-subject randomised control trial  

PubMed Central

Introduction Frequently, toe walking gait is the result of disease processes, trauma or neurogenic influences. Idiopathic toe walking (ITW) is, by definition, the diagnosis of a toe walking gait adopted in the absence of one of these medical conditions. Long-term ITW has been associated with reduced ankle range of motion. Reported treatments have included serial casting, Botulinum toxin type A or surgery to improve the ankle range of motion. Investigating the impact of simple and non-invasive treatment options for ITW is important for future research and clinical outcomes. This study investigates the immediate impact of footwear, footwear with orthotics and whole body vibration on ITW to determine if any one intervention improves heel contact and spatial-temporal gait measures. This determination is important for future clinical trials into treatment effectiveness. Methods and analysis Design: this protocol describes a within-subject randomised controlled trial that measures changes in gait following changes in external stimuli. Participants: 15 children diagnosed with an ITW gait will be recruited from the Victorian Paediatric Rehabilitation Service at Monash Children's Hospital Toe Walking Clinic provided they have ITW and meet the inclusion criteria. Procedure: participants will have their gait recorded walking barefoot, in usual footwear, a custom-made, full-length carbon fibre orthotic in usual footwear and following whole body vibration. Outcome measures will include the presence of bilateral heel contact preintervention and postintervention, stride length (cm), stride width (cm), left and right stride time (s), left and right stance and swing percentage of the gait cycle, gait velocity (m/s), left and right foot toe in/toe out angle (°) and weight-bearing lunge pre and post each condition. Ethics and dissemination The results of this study will be published at the conclusion and have been approved by Southern Health HREC:12102B. Clinical trial registry number ACTRN12612000975897. PMID:23454667

Williams, Cylie M; Michalitsis, Joanne; Murphy, Anna; Rawicki, Barry; Haines, Terry P

2013-01-01

74

Evaluation of a bisphosphonate enriched ultra-high molecular weight polyethylene for enhanced total joint replacement bearing surface functionality  

NASA Astrophysics Data System (ADS)

Each year in the United States there is an increasing trend of patients receiving total joint replacement (TJR) procedures. Approximately a half million total knee replacements (TKRs) are performed annually in the United States with increasing prevalence attributed to baby-boomers, obesity, older, and younger patients. This trend is also seen for total hip replacements (THRs) as well. The use of ultra high molecular weight polyethylene (UHMWPE) inserts in TJRs results in wear particle-induced osteolysis, which is the predominant cause for prosthesis failure and revision surgery. Sub-micron size particle generation is inevitable despite the numerous efforts in improving this bearing material. Work by others has shown that the use of oral and intravenous systemic bisphosphonates (BP) can significantly minimize periprosthetic osteolysis. However, the systemic delivery and the high solubility of BPs results in a predominant portion of the drug being excreted via the kidney without reaching its target, bone. This doctoral research project is focused on the development and evaluation of a novel method to administer BPs locally using the inherent wear of UHMWPE for possible use as an anti-osteolysis treatment. For new materials to be considered, they must be mechanically and tribologically comparable to the current gold standard, UHMWPE. In order to evaluate this material, mechanical, drug elution and tribological experiments were performed to allow assessment of material properties. Tensile tests showed comparable yield stress and pin-on-disk testing showed comparable wear to standard virgin UHMWPE. Further, drug elution tests have shown that BP was released from the enriched material both in static and dynamic conditions. Additionally, an aggressive 2 million cycle total knee simulator experiment has shown statistically similar wear results for the two materials. Overall, this research has provided the groundwork for further characterization and development of a new potential material for total joint replacements as an enhancement to standard UHMWPE. This material shows significant potential as an alternative bearing material to indirectly increase TJR longevity by addressing osteolysis related issues.

Wright-Walker, Cassandra Jane

75

Gait characteristic analysis and identification based on the iPhone's accelerometer and gyrometer.  

PubMed

Gait identification is a valuable approach to identify humans at a distance. In this paper, gait characteristics are analyzed based on an iPhone's accelerometer and gyrometer,and a new approach is proposed for gait identification. Specifically, gait datasets are collected by the triaxial accelerometer and gyrometer embedded in an iPhone. Then, the datasets are processed to extract gait characteristic parameters which include gait frequency, symmetry coefficient, dynamic range and similarity coefficient of characteristic curves. Finally, a weighted voting scheme dependent upon the gait characteristic parameters is proposed forgait identification. Four experiments are implemented to validate the proposed scheme. The attitude and acceleration solutions are verified by simulation. Then the gait characteristics are analyzed by comparing two sets of actual data, and the performance of the weighted voting identification scheme is verified by 40 datasets of 10 subjects. PMID:25222034

Sun, Bing; Wang, Yang; Banda, Jacob

2014-01-01

76

Phasic-to-tonic shift in trunk muscle activity relative to walking during low-impact weight bearing exercise  

NASA Astrophysics Data System (ADS)

The aim of this study was to investigate the influence of an exercise device, designed to improve the function of lumbopelvic muscles via low-impact weight-bearing exercise, on electromyographic (EMG) activity of lumbopelvic, including abdominal muscles. Surface EMG activity was collected from lumbar multifidus (LM), erector spinae (ES), internal oblique (IO), external oblique (EO) and rectus abdominis (RA) during overground walking (OW) and exercise device (EX) conditions. During walking, most muscles showed peaks in activity which were not seen during EX. Spinal extensors (LM, ES) were more active in EX. Internal oblique and RA were less active in EX. In EX, LM and ES were active for longer than during OW. Conversely, EO and RA were active for a shorter duration in EX than OW. The exercise device showed a phasic-to-tonic shift in activation of both local and global lumbopelvic muscles and promoted increased activation of spinal extensors in relation to walking. These features could make the exercise device a useful rehabilitative tool for populations with lumbopelvic muscle atrophy and dysfunction, including those recovering from deconditioning due to long-term bed rest and microgravity in astronauts.

Caplan, Nick; Gibbon, Karl; Hibbs, Angela; Evetts, Simon; Debuse, Dorothée

2014-11-01

77

The Online Gait Measurement for Characteristic Gait Animation Synthesis  

Microsoft Academic Search

\\u000a This paper presents a method to measure online the gait features from the gait silhouette images and to synthesize characteristic\\u000a gait animation for an audience-participant digital entertainment. First, both static and dynamic gait features are extracted\\u000a from the silhouette images captured by an online gait measurement system. Then, key motion data for various gaits are captured\\u000a and a new motion

Yasushi Makihara; Mayu Okumura; Yasushi Yagi; Shigeo Morishima

78

Longitudinal changes in poststroke spatiotemporal gait asymmetry over inpatient rehabilitation.  

PubMed

Background. Little information exists about longitudinal changes in spatiotemporal gait asymmetry during rehabilitation, despite it being a common goal. Objectives. To describe longitudinal changes in spatiotemporal gait asymmetry over rehabilitation and examine relationships with changes in other poststroke impairments. Methods. Retrospective chart reviews were conducted for 71 stroke rehabilitation inpatients. Admission and discharge measures of spatiotemporal symmetry, velocity, motor impairment, mobility and balance were extracted and change scores were calculated. Relationships between changes in spatiotemporal symmetry and other change scores were investigated with Spearman correlations. Individuals were divided into four groups (worse, no change-symmetric, no change-asymmetric, improved) based on (1) symmetry/asymmetry at admission and (2) symmetry change scores >minimal detectable change. Differences in change scores between groups were investigated with analyses of covariance using the admission value as a covariate. Results. At admission, 59% and 49% of individuals were asymmetric in swing time and step length, respectively. Of these individuals, 21% and 14% improved swing symmetry or step symmetry, respectively. In contrast, 30% improved gait velocity, 62% improved functional balance and 73% improved functional mobility. Associations between change in swing symmetry and change in paretic limb weight bearing in standing and change in step symmetry and change in velocity were significant. There were no significant differences in change scores between the symmetry groups. Conclusions. The majority of asymmetric stroke patients did not improve spatiotemporal asymmetry during rehabilitation despite the fact that velocity, balance and functional mobility improved. Future work should investigate other factors associated with improved spatiotemporal symmetry and interventions to specifically improve it. PMID:24826888

Patterson, Kara K; Mansfield, Avril; Biasin, Louis; Brunton, Karen; Inness, Elizabeth L; McIlroy, William E

2015-02-01

79

Three-Dimensional Gait Analysis Can Shed New Light on Walking in Patients with Haemophilia  

PubMed Central

In patients with haemophilia (PWH) (from Greek “blood love”), the long-term consequences of repeated haemarthrosis include cartilage damage and irreversible arthropathy, resulting in severe impairments in locomotion. Quantifying the extent of joint damage is therefore important in order to prevent disease progression and compare the efficacy of treatment strategies. Musculoskeletal impairments in PWH may stem from structural and functional abnormalities, which have traditionally been evaluated radiologically or clinically. However, these examinations are performed in a supine position (i.e., non-weight-bearing condition). We therefore suggest three-dimensional gait analysis (3DGA) as an innovative approach designed to focus on the functional component of the joint during the act of walking. This is of the utmost importance, as pain induced by weight-bearing activities influences the functional performance of the arthropathic joints significantly. This review endeavors to improve our knowledge of the biomechanical consequences of multiple arthropathies on gait pattern in adult patients with haemophilia using 3DGA. In PWH with arthropathy, the more the joint function was altered, the more the metabolic energy was consumed. 3DGA analysis could highlight the effect of an orthopedic disorder in PWH during walking. Indeed, mechanical and metabolic impairments were correlated to the progressive loss of active mobility into the joints. PMID:23766686

Lobet, Sébastien; Detrembleur, Christine; Massaad, Firas; Hermans, Cedric

2013-01-01

80

Osteochondral reconstruction of a non-weight-bearing joint using a high-density porous polyethylene implant.  

PubMed

Currently, there is no reliable reconstructive modality allowing anatomic resurfacing of traumatic digital osteochondral articular defects. The purpose of the present study is to demonstrate the utility of Medpor, a high-density porous polyethylene (HDPP) scaffold biomaterial that can (1) be readily contoured to fit any joint defect, (2) permit stable internal fixation, and (3) permit osteocyte and chondrocyte ingrowth and subsequent articular cartilage resurfacing necessary to restore joint congruity. HDPP has gained wide acceptance for use in craniofacial and skeletal reconstruction and augmentation. An avian non-weight-bearing joint model was designed to study the role of the HDPP implant in small joint reconstruction. An osteochondral defect was created with a 5-mm circular punch in the humeral articular surface of both glenohumeral joints of 32 adult White Leghorn chickens. In each animal, one defect was press-fitted with a correspondingly sized HDPP implant (HDPP implant group); the contralateral defect was filled with the original osteochondral plug (isograft group) or left unrepaired (control group). At 2 weeks, and 1, 3, and 6 months,joints from each group were harvested and evaluated. Over the 6-month study period, joints in the control group demonstrated healing with dense collagenous scar tissue leaving residual defects at the articular surfaces and significant degenerative disease of the glenohumeral joints radiographically. Joints in the isograft group demonstrated near-complete resorption with some preservation of the cartilaginous cap but overall depression of the articular surface and significant degenerative joint disease. Joints in the HDPP implant group demonstrated stable fixation by highly mineralized bony trabecular ingrowth, preservation of the articular contour of the humeral head, and no evidence of significant degenerative joint disease. These findings indicate a potential role for this high-density porous polyethylene implant in the reconstruction of small joint articular and osseous defects. PMID:11129184

Weinzweig, J; Pantaloni, M; Spangenberger, A; Marler, J; Zienowicz, R J

2000-12-01

81

Hamstrings cocontraction reduces internal rotation, anterior translation, and anterior cruciate ligament load in weight-bearing flexion.  

PubMed

Strengthening of the hamstrings is often recommended following injury and reconstruction of the anterior cruciate ligament. It has been suggested that hamstrings activity stabilizes the knee and reduces anterior cruciate ligament load during weight-bearing flexion; however, the effects of hamstrings cocontraction on the kinematics and mechanics of the normal knee have not been assessed at physiological load levels. The aim of this study was to determine whether the addition of hamstrings force affects knee rotations, translations, and joint and quadriceps force during flexion with loads at physiological levels applied to the muscles and joints. Eight cadaveric knee specimens were tested with a servohydraulic mechanism capable of applying controlled dynamic loads to simulate quadriceps and hamstrings muscle forces throughout a physiological range of motion. A constant vertical load of physiologic magnitude was applied to the hip, and quadriceps force was varied to maintain equilibrium throughout flexion. Two conditions were tested: no hamstrings force and a constant hamstrings force equivalent to the vertical load. Hamstrings force significantly reduced internal rotation (p<0.0001) and anterior translation (p<0.0001), increased quadriceps force (p<0.0001) and normal resultant force on the tibia (p<0.0001), and reversed the direction of the shear force on the tibia (p<0.0001). These results suggest that hamstrings strengthening following anterior cruciate ligament injury may benefit anterior cruciate ligament-deficient and reconstructed knees by reducing the load in the ligament; however, they also imply that this comes at the expense of efficiency and higher patellofemoral and joint forces. PMID:10632447

MacWilliams, B A; Wilson, D R; DesJardins, J D; Romero, J; Chao, E Y

1999-11-01

82

A mobile gait monitoring system for gait analysis  

Microsoft Academic Search

Conventional gait rehabilitation treatment does not provide quantitative and graphical information on abnormal gait kinematics, and the match of the intervention strategy to the underlying clinical presentation may be limited by clinical expertise and experience. In this paper, a mobile gait monitoring system (MGMS) is proposed, which helps patients self correct their gait without restriction of time and place. The

Joonbum Bae; Kyoungchul Kong; Nancy Byl; Masayoshi Tomizuka

2009-01-01

83

Partial versus unrestricted weight bearing after an uncemented femoral stem in total hip arthroplasty: recommendation of a concise rehabilitation protocol from a systematic review of the literature  

Microsoft Academic Search

The aim of this systematic review was to find evidence-based support in the literature to allow immediate unrestricted weight\\u000a bearing after primary uncemented total hip arthroplasty (THA). Accelerated rehabilitation programs for THA are becoming increasingly\\u000a popular to shorten hospital stay and to facilitate rapid restoration of function. The goals of these rehabilitation programs\\u000a could be more easily achieved if immediate

A. M. Hol; S. van Grinsven; C. Lucas; J. L. C. van Susante; C. J. M. van Loon

2010-01-01

84

A weight-bearing, water-based exercise program for osteopenic women: Its impact on bone, functional fitness, and well-being  

Microsoft Academic Search

Objective: To evaluate the effects of a weight-bearing, waterbased, exercise program designed for women with low bone mass.Design: A test-retest cross-sectional, prospective study.Setting: Community-dwelling women from a Canadian city.Participants: Seventy-seven postmenopausal women, 50 to 70 years of age, with spinal or femoral bone density below the fracture threshold.Intervention: Subjects exercised in a pool with waist-high water for 60 minutes, 3

Gina Bravo; Pierre Gauthier; Pierre-Michel Roy; Hélène Payette; Philippe Gaulin

1997-01-01

85

Balancing the Rates of New Bone Formation and Polymer Degradation Enhances Healing of Weight-Bearing Allograft/Polyurethane Composites in Rabbit Femoral Defects  

PubMed Central

There is a compelling clinical need for bone grafts with initial bone-like mechanical properties that actively remodel for repair of weight-bearing bone defects, such as fractures of the tibial plateau and vertebrae. However, there is a paucity of studies investigating remodeling of weight-bearing bone grafts in preclinical models, and consequently there is limited understanding of the mechanisms by which these grafts remodel in vivo. In this study, we investigated the effects of the rates of new bone formation, matrix resorption, and polymer degradation on healing of settable weight-bearing polyurethane/allograft composites in a rabbit femoral condyle defect model. The grafts induced progressive healing in vivo, as evidenced by an increase in new bone formation, as well as a decrease in residual allograft and polymer from 6 to 12 weeks. However, the mismatch between the rates of autocatalytic polymer degradation and zero-order (independent of time) new bone formation resulted in incomplete healing in the interior of the composite. Augmentation of the grafts with recombinant human bone morphogenetic protein-2 not only increased the rate of new bone formation, but also altered the degradation mechanism of the polymer to approximate a zero-order process. The consequent matching of the rates of new bone formation and polymer degradation resulted in more extensive healing at later time points in all regions of the graft. These observations underscore the importance of balancing the rates of new bone formation and degradation to promote healing of settable weight-bearing bone grafts that maintain bone-like strength, while actively remodeling. PMID:23941405

Dumas, Jerald E.; Prieto, Edna M.; Zienkiewicz, Katarzyna J.; Guda, Teja; Wenke, Joseph C.; Bible, Jesse; Holt, Ginger E.

2014-01-01

86

A 1-year combined weight-bearing training program is beneficial for bone mineral density and neuromuscular function in older women  

Microsoft Academic Search

Forty-eight community living women 66–87 years old volunteered to participate in a 12-month prospective, randomized, controlled, trial. The aim was to determine if a combined weight-bearing training program twice a week would be beneficial to bone mineral density and neuromuscular function. The participants were pairwise age-matched and randomly assigned to either an exercise group (n=24) or a control group (n=24).

Undis Englund; Håkan Littbrand; Anna Sondell; Ulrika Pettersson; Gustaf Bucht

2005-01-01

87

Balancing the rates of new bone formation and polymer degradation enhances healing of weight-bearing allograft/polyurethane composites in rabbit femoral defects.  

PubMed

There is a compelling clinical need for bone grafts with initial bone-like mechanical properties that actively remodel for repair of weight-bearing bone defects, such as fractures of the tibial plateau and vertebrae. However, there is a paucity of studies investigating remodeling of weight-bearing bone grafts in preclinical models, and consequently there is limited understanding of the mechanisms by which these grafts remodel in vivo. In this study, we investigated the effects of the rates of new bone formation, matrix resorption, and polymer degradation on healing of settable weight-bearing polyurethane/allograft composites in a rabbit femoral condyle defect model. The grafts induced progressive healing in vivo, as evidenced by an increase in new bone formation, as well as a decrease in residual allograft and polymer from 6 to 12 weeks. However, the mismatch between the rates of autocatalytic polymer degradation and zero-order (independent of time) new bone formation resulted in incomplete healing in the interior of the composite. Augmentation of the grafts with recombinant human bone morphogenetic protein-2 not only increased the rate of new bone formation, but also altered the degradation mechanism of the polymer to approximate a zero-order process. The consequent matching of the rates of new bone formation and polymer degradation resulted in more extensive healing at later time points in all regions of the graft. These observations underscore the importance of balancing the rates of new bone formation and degradation to promote healing of settable weight-bearing bone grafts that maintain bone-like strength, while actively remodeling. PMID:23941405

Dumas, Jerald E; Prieto, Edna M; Zienkiewicz, Katarzyna J; Guda, Teja; Wenke, Joseph C; Bible, Jesse; Holt, Ginger E; Guelcher, Scott A

2014-01-01

88

In Vivo Motion of Femoral Condyles During Weight-Bearing Flexion After Anterior Cruciate Ligament Rupture Using Biplane Radiography  

PubMed Central

The purpose of this study was to investigate in vivo three- dimensional tibiofemoral kinematics and femoral condylar motion in knees with anterior cruciate ligament (ACL) deficiency during a knee bend activity. Ten patients with unilateral ACL rupture were enrolled. Both the injured and contralateral normal knees were imaged using biplane radiography at extension and at 15°, 30°, 60°, 90°, and 120° of flexion. Bilateral knees were next scanned by computed tomography, from which bilateral three-dimensional knee models were created. The in vivo tibiofemoral motion at each flexion position was reproduced through image registration using the knee models and biplane radiographs. A joint coordinate system containing the geometric center axis of the femur was used to measure the tibiofemoral motion. In ACL deficiency, the lateral femoral condyle was located significantly more posteriorly at extension and at 15° (p < 0.05), whereas the medial condylar position was changed only slightly. This constituted greater posterior translation and external rotation of the femur relative to the tibia at extension and at 15° (p < 0.05). Furthermore, ACL deficiency led to a significantly reduced extent of posterior movement of the lateral condyle during flexion from 15° to 60° (p < 0.05). Coupled with an insignificant change in the motion of the medial condyle, the femur moved less posteriorly with reduced extent of external rotation during flexion from 15° to 60° in ACL deficiency (p < 0.05). The medial- lateral and proximal-distal translations of the medial and lateral condyles and the femoral adduction-abduction rotation were insignificantly changed after ACL deficiency. The results demonstrated that ACL deficiency primarily changed the anterior-posterior motion of the lateral condyle, producing not only posterior subluxation at low flexion positions but also reduced extent of posterior movement during flexion from 15° to 60°. Key Points Three-dimensional tibiofemoral kinematics and femoral condylar motion in ACL-deficient knees during upright weight-bearing flexion were measured using biplane radiography with the geometric center axis. ACL deficiency caused posterior subluxation of the lateral condyle with excess external femoral rotation at early flexion positions. On flexion from 15° to 60°, the lateral condyle moved slightly posteriorly in ACL deficiency leading to reduced extent of external femoral rotation. PMID:24149168

Chen, Kaining; Yin, Li; Cheng, Liangjun; Li, Chuan; Chen, Cheng; Yang, Liu

2013-01-01

89

Magnetic Bearing  

NASA Technical Reports Server (NTRS)

AVCON, Inc. produces advanced magnetic bearing systems for industrial use, offering a unique technological approach based on contract work done at Marshall Space Flight Center and Lewis Research Center. Designed for the turbopump of the Space Shuttle main engine, they are now used in applications such as electric power generation, petroleum refining, machine tool operation and natural gas pipelines. Magnetic bearings support moving machinery without physical contact; AVCON's homopolar approach is a hybrid of permanent and electromagnets which are one-third the weight, smaller and more power- efficient than previous magnetic bearings.

1996-01-01

90

Multidirectional transparent support for overground gait training.  

PubMed

Gait and balance training is an essential ingredient for locomotor rehabilitation of patients with neurological impairments. Robotic overhead support systems may help these patients train, for example by relieving them of part of their body weight. However, there are only very few systems that provide support during overground gait, and these suffer from limited degrees of freedom and/or undesired interaction forces due to uncompensated robot dynamics, namely inertia. Here, we suggest a novel mechanical concept that is based on cable robot technology and that allows three-dimensional gait training while reducing apparent robot dynamics to a minimum. The solution does not suffer from the conventional drawback of cable robots, which is a limited workspace. Instead, displaceable deflection units follow the human subject above a large walking area. These deflection units are not actuated, instead they are implicitly displaced by means of the forces in the cables they deflect. This leads to an underactuated design, because the deflection units cannot be moved arbitrarily. However, the design still allows accurate control of a three-dimensional force vector acting on a human subject during gait. We describe the mechanical concept, the control concept, and we show first experimental results obtained with the device, including the force control performance during robot-supported overground gait of five human subjects without motor impairments. PMID:24187327

Vallery, H; Lutz, P; von Zitzewitz, J; Rauter, G; Fritschi, M; Everarts, C; Ronsse, R; Curt, A; Bolliger, M

2013-06-01

91

Abstract--In this paper, we explain that the human knee behavior in the weight acceptance phase of gait (first ~40% of  

E-print Network

, enhancement of load carrying capacity, reduction of fatigue, and improvement of posture [1]. Research Abstract-- In this paper, we explain that the human knee behavior in the weight acceptance phase exoskeletons emerged to improve the performance of humans via reduction of metabolic cost of walking

Dollar, Aaron M.

92

Technological Advances in Interventions to Enhance Post-Stroke Gait  

PubMed Central

Synopsis This article provides a comprehensive review of specific rehabilitation interventions used to enhance hemiparetic gait following stroke. Neurologic rehabilitation interventions may be either therapeutic resulting in enhanced motor recovery or compensatory whereby assistance or substitution for neurological deficits results in improved functional performance. Included in this review are lower extremity functional electrical stimulation (FES), body-weight supported treadmill training (BWSTT), and lower extremity robotic-assisted gait training. These post-stroke gait training therapies are predicated on activity-dependent neuroplasticity which is the concept that cortical reorganization following central nervous system injury may be induced by repetitive, skilled, and cognitively engaging active movement. All three interventions have been trialed extensively in both research and clinical settings to demonstrate a positive effect on various gait parameters and measures of walking performance. However, more evidence is necessary to determine if specific technology-enhanced gait training methods are superior to conventional gait training methods. This review provides an overview of evidence-based research which supports the efficacy of these three interventions to improve gait, as well as provide perspective on future developments to enhance post-stroke gait in neurologic rehabilitation. PMID:23598265

Sheffler, Lynne R.; Chae, John

2012-01-01

93

Gait rehabilitation machines based on programmable footplates  

PubMed Central

Background Gait restoration is an integral part of rehabilitation of brain lesioned patients. Modern concepts favour a task-specific repetitive approach, i.e. who wants to regain walking has to walk, while tone-inhibiting and gait preparatory manoeuvres had dominated therapy before. Following the first mobilization out of the bed, the wheelchair-bound patient should have the possibility to practise complex gait cycles as soon as possible. Steps in this direction were treadmill training with partial body weight support and most recently gait machines enabling the repetitive training of even surface gait and even of stair climbing. Results With treadmill training harness-secured and partially relieved wheelchair-mobilised patients could practise up to 1000 steps per session for the first time. Controlled trials in stroke and SCI patients, however, failed to show a superior result when compared to walking exercise on the floor. Most likely explanation was the effort for the therapists, e.g. manually setting the paretic limbs during the swing phase resulting in a too little gait intensity. The next steps were gait machines, either consisting of a powered exoskeleton and a treadmill (Lokomat, AutoAmbulator) or an electromechanical solution with the harness secured patient placed on movable foot plates (Gait Trainer GT I). For the latter, a large multi-centre trial with 155 non-ambulatory stroke patients (DEGAS) revealed a superior gait ability and competence in basic activities of living in the experimental group. The HapticWalker continued the end effector concept of movable foot plates, now fully programmable and equipped with 6 DOF force sensors. This device for the first time enables training of arbitrary walking situations, hence not only the simulation of floor walking but also for example of stair climbing and perturbations. Conclusion Locomotor therapy is a fascinating new tool in rehabilitation, which is in line with modern principles of motor relearning promoting a task-specific repetitive approach. Sophisticated technical developments and positive randomized controlled trials form the basis of a growing acceptance worldwide to the benefits or our patients. PMID:17291335

Schmidt, Henning; Werner, Cordula; Bernhardt, Rolf; Hesse, Stefan; Krüger, Jörg

2007-01-01

94

Gait Analysis Using Wearable Sensors  

PubMed Central

Gait analysis using wearable sensors is an inexpensive, convenient, and efficient manner of providing useful information for multiple health-related applications. As a clinical tool applied in the rehabilitation and diagnosis of medical conditions and sport activities, gait analysis using wearable sensors shows great prospects. The current paper reviews available wearable sensors and ambulatory gait analysis methods based on the various wearable sensors. After an introduction of the gait phases, the principles and features of wearable sensors used in gait analysis are provided. The gait analysis methods based on wearable sensors is divided into gait kinematics, gait kinetics, and electromyography. Studies on the current methods are reviewed, and applications in sports, rehabilitation, and clinical diagnosis are summarized separately. With the development of sensor technology and the analysis method, gait analysis using wearable sensors is expected to play an increasingly important role in clinical applications. PMID:22438763

Tao, Weijun; Liu, Tao; Zheng, Rencheng; Feng, Hutian

2012-01-01

95

New Locomotion Gaits  

Microsoft Academic Search

This paper investigates new modes of robot land locomotion, in particular statically stable non-wheeled, non-tracked locomotion. These locomotion gaits are accomplished by a reconfigurable modular robot called Polypod using a control scheme combining a small number of primitive control modes for each module. The design of Polypod is first reviewed, then two and three-dimensional locomotion gaits are described along with

Mark Yim

1994-01-01

96

Comparison of Upright Gait with Supine Bungee-Cord Gait  

NASA Technical Reports Server (NTRS)

Running on a treadmill with bungee-cord resistance is currently used on the Russian space station MIR as a countermeasure for the loss of bone and muscular strength which occurs during spaceflight. However, it is unknown whether ground reaction force (GRF) at the feet using bungee-cord resistance is similar to that which occurs during upright walking and running on Earth. We hypothesized-that the DRAMs generated during upright walking and running are greater than the DRAMs generated during supine bungee-cord gait. Eleven healthy subjects walked (4.8 +/- 0.13 km/h, mean +/- SE) and ran (9.1 +/- 0.51 km/h) during upright and supine bungee-cord exercise on an active treadmill. Subjects exercised for 3 min in each condition using a resistance of 1 body weight calibrated during an initial, stationary standing position. Data were sampled at a frequency of 500Hz and the mean of 3 trials was analyzed for each condition. A repeated measures analysis of variance tested significance between the conditions. Peak DRAMs during upright walking were significantly greater (1084.9 +/- 111.4 N) than during supine bungee-cord walking (770.3 +/- 59.8 N; p less than 0.05). Peak GRFs were also significantly greater for upright running (1548.3 +/- 135.4 N) than for supine bungee-cord running (1099.5 +/- 158.46 N). Analysis of GRF curves indicated that forces decreased throughout the stance phase for bungee-cord gait but not during upright gait. These results indicate that bungee-cord exercise may not create sufficient loads at the feet to counteract the loss of bone and muscular strength that occurs during long-duration exposure to microgravity.

Boda, Wanda L.; Hargens, Alan R.; Campbell, J. A.; Yang, C.; Holton, Emily M. (Technical Monitor)

1998-01-01

97

A procedure for weighted summation of the derivatives of reflection coefficients in adaptive Schur filter with application to fault detection in rolling element bearings  

NASA Astrophysics Data System (ADS)

A procedure for feature extraction using adaptive Schur filter for damage detection in rolling element bearings is proposed in the paper. Damaged bearings produce impact signals (shocks) related with local change (loss) of stiffness in pairs: inner/outer race-rolling element. If significant disturbances do not occur (i.e. signal to noise ratio is sufficient), diagnostics is not very complicated and usually envelope analysis is used. Unfortunately, in most industrial examples, these impulsive contributions in vibration are completely masked by noise or other high energy sources. Moreover, impulses may have time varying amplitudes caused by transmission path, load and properties of noise changing in time. Thus, in order to extract time varying signal of interest, the solution would be an adaptive one. The proposed approach is based on the normalized exact least-square time-variant lattice filter (adaptive Schur filter). It is characterized by an extremely fast start-up performance, excellent convergence behavior, and fast parameter tracking capability, making this approach interesting. Schur adaptive filter consists of P sections, estimating, among others, time-varying reflection coefficients (RCs). In this paper it is proposed to use RCs and their derivatives as diagnostic features. However, it is not convenient to analyze simultaneously P signals for P sections, so instead of these, weighted sum of derivatives of RCs can be used. The key question is how to find these weight values for summation procedure. An original contributions are: application of Schur filter to bearings vibration processing, proposal of several features that can be used for detection and mentioned procedure of weighted summation of signal from sections of Schur filter. The method of signal processing is well-adapted for analysis of the non-stationary time-series, so it sounds very promising for diagnostics of machines working in time varying load/speed conditions.

Makowski, Ryszard; Zimroz, Radoslaw

2013-07-01

98

Parenteral administration of twin-bearing ewes with L-arginine enhances the birth weight and brown fat stores in sheep.  

PubMed

The objective of this study was to evaluate the effects of parenteral administration of L-arginine (Arg) to well-fed twin-bearing ewes from day (d) 100 of pregnancy to birth on fetal growth, body composition and neonatal behavior. Ewes received an i.v. bolus of either 345 ?mol Arg-HCl/kg bodyweight or saline solution (control) 3 times a day. At d 140 of pregnancy, Arg-supplemented and control ewes were euthanized and fetal weight and fetal organ weight recorded, and maternal and fetal plasma concentrations of amino acids, hormones and metabolites analyzed. A subset of ewes was allowed to lamb and birth weight, body dimensions and behavior of the lambs in the first 2 hours(h) following birth recorded and blood samples collected. At d 140 of pregnancy, fetal weight internal organ weights were unaffected by treatment with the exception of brown fat stores which were increased by 16% in fetuses from Arg-supplemented ewes relative to controls (P < 0.05). At birth, there was an interaction (P = 0.06) between treatment and sex for birth weight of the lamb. The ewe lambs from Arg-supplemented ewes were 12% (P < 0.05) heavier at birth compared with controls whereas birth weight of male lambs did not differ. These results indicate that maternal Arg supplementation enhanced brown fat stores in the fetus and countered some effect of fetal growth restriction due to litter size in female lambs. Increasing birth weight of female lambs and enhancing brown fat stores of all lambs may have important implications for lamb survival and postnatal growth. PMID:24422179

McCoard, Sue; Sales, Francisco; Wards, Nina; Sciascia, Quentin; Oliver, Mark; Koolaard, John; van der Linden, Danitsja

2013-01-01

99

Exercises to Improve Gait Abnormalities  

MedlinePLUS

... Home About Goals Articles Directories Videos Resources Contact Exercises to Improve Gait Abnormalities Home » Article Categories » Exercise and Fitness Font Size: A A A A Exercises to Improve Gait Abnormalities Next Page The manner ...

100

In vivo regulation of the beta-myosin heavy chain gene in soleus muscle of suspended and weight-bearing rats  

NASA Technical Reports Server (NTRS)

In the weight-bearing hindlimb soleus muscle of the rat, approximately 90% of muscle fibers express the beta-myosin heavy chain (beta-MHC) isoform protein. Hindlimb suspension (HS) causes the MHC isoform population to shift from beta toward the fast MHC isoforms. Our aim was to establish a model to test the hypothesis that this shift in expression is transcriptionally regulated through specific cis elements of the beta-MHC promoter. With the use of a direct gene transfer approach, we determined the activity of different length beta-MHC promoter fragments, linked to a firefly luciferase reporter gene, in soleus muscle of control and HS rats. In weight-bearing rats, the relative luciferase activity of the longest beta-promoter fragment (-3500 bp) was threefold higher than the shorter promoter constructs, which suggests that an enhancer sequence is present in the upstream promoter region. After 1 wk of HS, the reporter activities of the -3500-, -914-, and -408-bp promoter constructs were significantly reduced ( approximately 40%), compared with the control muscles. However, using the -215-bp construct, no differences in promoter activity were observed between HS and control muscles, which indicates that the response to HS in the rodent appears to be regulated within the -408 and -215 bp of the promoter.

Giger, J. M.; Haddad, F.; Qin, A. X.; Baldwin, K. M.

2000-01-01

101

Weight Gain Does Not Preclude Increased Ubiquitin Conjugation in Skeletal Muscle: An Exploratory Study in Tumor-Bearing Mice  

Microsoft Academic Search

Background and Hypothesis: At least 13 studies have shown that the ubiquitin-proteasome system mediates muscle wasting in weight-losing cancer subjects. We hypothesized that cancer itself may activate the ubiquitin-proteasome system, regardless of weight loss. Methods: We utilized hybrid mice obtained by crossing Mouse Mammary Tumor Virus-Transforming Growth Factor-? (TGF-?) mice with the Lepob strain. Five hybrid MMTV-TGF-? heterozygous Lep+Lepob female

Aminah Jatoi; Margot P. Cleary; Cheow-Meng Tee; Phuong L. Nguyen

2001-01-01

102

Context based gait recognition  

NASA Astrophysics Data System (ADS)

Gait recognition has recently become a popular topic in the field of biometrics. However, the main hurdle is the insufficient recognition rate in the presence of low quality samples. The main focus of this paper is to investigate how the performance of a gait recognition system can be improved using additional information about behavioral patterns of users and the context in which samples have been taken. The obtained results show combining the context information with biometric data improves the performance of the system at a very low cost. The amount of improvement depends on the distinctiveness of the behavioral patterns and the quality of the gait samples. Using the appropriate distinctive behavioral models it is possible to achieve a 100% recognition rate.

Bazazian, Shermin; Gavrilova, Marina

2012-06-01

103

Effective one step-iterative fiducial marker-based compensation for involuntary motion in weight-bearing C-arm cone-beam CT scanning of knees  

NASA Astrophysics Data System (ADS)

We previously introduced three different fiducial marker-based correction methods (2D projection shifting, 2D projection warping, and 3D image warping) for patients' involuntary motion in the lower body during weight-bearing Carm CT scanning. The 3D warping method performed better than 2D methods since it could more accurately take into account the lower body motion in 3D. However, as the 3D warping method applies different rotational and translational movement to the reconstructed image for each projection frame, distance-related weightings were slightly twisted and thus result in overlaying background noise over the entire image. In order to suppress background noise and artifacts (e.g. metallic marker-caused streaks), the 3D warping method has been improved by incorporating bilateral filtering and a Landwebertype iteration in one step. A series of projection images of five healthy volunteers standing at various flexion angles were acquired using a C-arm cone-beam CT system with a flat panel. A horizontal scanning trajectory of the C-arm was calibrated to generate projection matrices. Using the projection matrices, the static reference marker coordinates in 3D were estimated and used for the improved 3D warping method. The improved 3D warping method effectively reduced background noise down below the noise level of 2D methods and also eliminated metal-generated streaks. Thus, improved visibility of soft tissue structures (e.g. fat and muscle) was achieved while maintaining sharp edges at bone-tissue interfaces. Any high resolution weight-bearing cone-beam CT system can apply this method for motion compensation.

Choi, Jang-Hwan; Maier, Andreas; Berger, Martin; Fahrig, Rebecca

2014-03-01

104

Short-term effects of self-mobilization with a strap on pain and range of motion of the wrist joint in patients with dorsal wrist pain when weight bearing through the hand: a case series.  

PubMed

Dorsal wrist pain frequently occurs in weight bearing through the hand in patients with distal radius stress injuries, scaphoid impaction syndrome, and dorsal impingement. To improve the wrist extension motion, joint mobilization has been used. However, there is no report on the effects of mobilization on the range of motion (ROM) and pain onset in patients with dorsal wrist pain when weight bearing through the hand. This study determined the effects of self-mobilization with a strap (SMWS) while weight bearing through the hand on the ROM and force generated at the onset of pain (FGOP) and intensity in the wrist joints of patients with dorsal wrist pain. Fifteen patients (six men, nine women) with dorsal wrist pain during weight bearing through the hand were recruited from a workplace-based work-conditioning center. SMWS was applied during five visits for a 1-week period. Both passive and active wrist extension ROM, FGOP, and pain intensity (PI) while pushing down through the hand were measured before and after SMWS. Passive and active ROM of wrist extension and FGOP increased significantly after the five sessions over 1 week of SMWS (p < 0.05). PI decreased significantly after the five sessions of SMWS (p < 0.05). These results suggest that SMWS can be used to increase wrist extension ROM and decrease wrist pain in patients with dorsal wrist pain during weight bearing through the hand. PMID:23830868

Choung, Sung-Dae; Kwon, Oh-Yun; Park, Kyue-Nam; Kim, Si-Hyun; Cynn, Heon-Seock

2013-12-01

105

Gait Stability following Concussion  

Microsoft Academic Search

PARKER, T. M., L. R. OSTERNIG, P. VAN DONKELAAR, and L. CHOU. Gait Stability following Concussion. Med. Sci. Sports Exerc., Vol. 38, No. 6, pp. 1032 - 1040, 2006. Introduction: The need to identify functional impairment following a brain injury is critical to prevent reinjury during the period of recovery. However, little is known about the effect of concussion on

TONYA M. PARKER; LOUIS R. OSTERNIG; PAUL VAN DONKELAAR; LI-SHAN CHOU

2006-01-01

106

Slowness in elderly gait  

Microsoft Academic Search

The aim of this research was to better understand how gait slows with age. We analyzed the kinematic parameters of locomotion (velocity, stride length, cycle duration, swing and double support durations), and their interrelationships both in the slowing process due to aging and in intentional modulations of velocity. The experiments were carried out on a group of 67 elderly adults

Anne-Marie Ferrandez; Jean Pailhous; Madeleine Durup

1990-01-01

107

Growth hormone, IGF-I, and exercise effects on non-weight-bearing fast muscles of hypophysectomized rats  

NASA Technical Reports Server (NTRS)

The effects of growth hormone (GH) or insulin-like growth factor I (IGF-I) with or without exercise (ladder climbing) in countering the effects of unweighting on fast muscles of hypophysectomized rats during 10 days of hindlimb suspension were determined. Compared with untreated suspended rats, muscle weights were 16-29% larger in GH-treated and 5-15% larger in IGF-I-treated suspended rats. Exercise alone had no effect on muscle weights. Compared with ambulatory control, the medial gastrocnemius weight in suspended, exercised rats was larger after GH treatment and maintained with IGF-I treatment. The combination of GH or IGF-I plus exercise in suspended rats resulted in an increase in size of each predominant fiber type, i.e., types I, I + IIa and IIa + IIx, in the medial gastrocnemius compared with untreated suspended rats. Normal ambulation or exercise during suspension increased the proportion of fibers expressing embryonic myosin heavy chain in hypophysectomized rats. The phenotype of the medial gastrocnemius was minimally affected by GH, IGF-I, and/or exercise. These results show that there is an IGF-I, as well as a GH, and exercise interactive effect in maintaining medial gastrocnemius fiber size in suspended hypophysectomized rats.

Grossman, E. J.; Grindeland, R. E.; Roy, R. R.; Talmadge, R. J.; Evans, J.; Edgerton, V. R.

1997-01-01

108

A method to standardize gait and balance variables for gait velocity  

Microsoft Academic Search

Many gait and balance variables depend on gait velocity, which seriously hinders the interpretation of gait and balance data derived from walks at different velocities. However, as far as we know there is no widely accepted method to correct for effects of gait velocity on other gait and balance measures. We developed a simple statistical method to obtain gait and

Marianne B. van Iersel; Marcel G. M. Olde Rikkert; George F. Borm

2007-01-01

109

Hormone replacement therapy does not augment gains in muscle strength or fat-free mass in response to weight-bearing exercise.  

PubMed

Lower extremity strength and fat-free mass were examined in 58 postmenopausal women aged 60-72 yr. Subjects were studied before and after an 11-mo control period (n = 16) or before and after an 11-mo weight-bearing exercise training program designed to generate relatively high ground reaction forces (n = 42). Twenty-two of the exercisers initiated hormone replacement therapy (HRT) at the outset of exercise and continued HRT for 11 mo. Hip extension and abduction strength were assessed using a hand-held dynamometer. Force production during knee extension and flexion was evaluated on an isokinetic dynamometer at 60, 90, and 180 degrees/s. Simultaneous knee and hip extension strength was also assessed on a leg press machine. Total body and lower extremity fat-free mass were determined using dual-energy x-ray absorptiometry. There were no significant changes in muscle strength or body composition in control subjects. Both exercise groups had significant increases in fat-free mass and in all strength measures. Fat-free mass increased from 38.8 +/- 4.3 to 39.7 +/- 4.3 kg in the exercise group and from 37.7 +/- 3.9 to 38.9 +/- 4.6 kg in the exercise-plus-HRT group. The average relative increase in strength was 16.2 +/- 11.0% in the exercise group and 17.0 +/- 13.0% in the exercise-plus-HRT group. Women receiving HRT did not have a gain in fat-free mass or in strength over and above that demonstrated by the women not on HRT. Our results provide evidence that HRT does not augment the increases in muscle mass or strength that occur in response to weight-bearing exercise in older women. PMID:9158551

Brown, M; Birge, S J; Kohrt, W M

1997-05-01

110

In vivo Contact Kinematics and Contact Forces of the Knee After Total Knee Arthroplasty During Dynamic Weight-bearing Activities  

PubMed Central

Analysis of polyethylene component wear and implant loosening in total knee arthroplasty (TKA) requires precise knowledge of in vivo articular motion and loading conditions. This study presents a simultaneous, in vivo measurement of tibiofemoral articular contact forces and contact kinematics in three TKA patients. These measurements were accomplished via a dual fluoroscopic imaging system and instrumented tibial implants during dynamic single leg lunge and chair rising-sitting. The measured forces and contact locations were also used to determine mediolateral distribution of axial contact forces. Contact kinematics data showed a medial pivot during flexion of the knee, for all patients in the study. Average axial forces were higher for lunge compared to chair rising-sitting (224% body weight vs. 187% body weight). In this study we measured peak anteroposterior and mediolateral forces averaging 13.3% BW, during lunge and 18.5% BW during chair rising-sitting. Mediolateral distributions of axial contact force were both patient and activity specific. All patients showed equitable medial-lateral loading during lunge but greater loads at the lateral compartment during chair rising-sitting. The results of this study may enable more accurate reproduction of in vivo loads and articular motion patterns in wear simulators and finite element models. This in turn may help advance our understanding of factors limiting longevity of TKA implants, such as aseptic loosening and polyethylene component wear, and enable improved TKA designs. PMID:18538328

Varadarajan, Kartik M.; Moynihan, Angela; D’Lima, Darryl; Colwell, Clifford W.; Li, Guoan

2011-01-01

111

In vivo contact kinematics and contact forces of the knee after total knee arthroplasty during dynamic weight-bearing activities.  

PubMed

Analysis of polyethylene component wear and implant loosening in total knee arthroplasty (TKA) requires precise knowledge of in vivo articular motion and loading conditions. This study presents a simultaneous in vivo measurement of tibiofemoral articular contact forces and contact kinematics in three TKA patients. These measurements were accomplished via a dual fluoroscopic imaging system and instrumented tibial implants, during dynamic single leg lunge and chair rising-sitting. The measured forces and contact locations were also used to determine mediolateral distribution of axial contact forces. Contact kinematics data showed a medial pivot during flexion of the knee, for all patients in the study. Average axial forces were higher for lunge compared to chair rising-sitting (224% vs. 187% body weight). In this study, we measured peak anteroposterior and mediolateral forces averaging 13.3% BW during lunge and 18.5% BW during chair rising-sitting. Mediolateral distributions of axial contact force were both patient and activity specific. All patients showed equitable medial-lateral loading during lunge but greater loads at the lateral compartment during chair rising-sitting. The results of this study may enable more accurate reproduction of in vivo loads and articular motion patterns in wear simulators and finite element models. This in turn may help advance our understanding of factors limiting longevity of TKA implants, such as aseptic loosening and polyethylene component wear, and enable improved TKA designs. PMID:18538328

Varadarajan, Kartik M; Moynihan, Angela L; D'Lima, Darryl; Colwell, Clifford W; Li, Guoan

2008-07-19

112

Fiducial marker-based correction for involuntary motion in weight-bearing C-arm CT scanning of knees. II. Experiment  

SciTech Connect

Purpose: A C-arm CT system has been shown to be capable of scanning a single cadaver leg under loaded conditions by virtue of its highly flexible acquisition trajectories. In Part I of this study, using the 4D XCAT-based numerical simulation, the authors predicted that the involuntary motion in the lower body of subjects in weight-bearing positions would seriously degrade image quality and the authors suggested three motion compensation methods by which the reconstructions could be corrected to provide diagnostic image quality. Here, the authors demonstrate that a flat-panel angiography system is appropriate for scanning both legs of subjectsin vivo under weight-bearing conditions and further evaluate the three motion-correction algorithms using in vivo data. Methods: The geometry of a C-arm CT system for a horizontal scan trajectory was calibrated using the PDS-2 phantom. The authors acquired images of two healthy volunteers while lying supine on a table, standing, and squatting at several knee flexion angles. In order to identify the involuntary motion of the lower body, nine 1-mm-diameter tantalum fiducial markers were attached around the knee. The static mean marker position in 3D, a reference for motion compensation, was estimated by back-projecting detected markers in multiple projections using calibrated projection matrices and identifying the intersection points in 3D of the back-projected rays. Motion was corrected using three different methods (described in detail previously): (1) 2D projection shifting, (2) 2D deformable projection warping, and (3) 3D rigid body warping. For quantitative image quality analysis, SSIM indices for the three methods were compared using the supine data as a ground truth. Results: A 2D Euclidean distance-based metric of subjects’ motion ranged from 0.85 mm (±0.49 mm) to 3.82 mm (±2.91 mm) (corresponding to 2.76 to 12.41 pixels) resulting in severe motion artifacts in 3D reconstructions. Shifting in 2D, 2D warping, and 3D warping improved the SSIM in the central slice by 20.22%, 16.83%, and 25.77% in the data with the largest motion among the five datasets (SCAN5); improvement in off-center slices was 18.94%, 29.14%, and 36.08%, respectively. Conclusions: The authors showed that C-arm CT control can be implemented for nonstandard horizontal trajectories which enabled us to scan and successfully reconstruct both legs of volunteers in weight-bearing positions. As predicted using theoretical models, the proposed motion correction methods improved image quality by reducing motion artifacts in reconstructions; 3D warping performed better than the 2D methods, especially in off-center slices.

Choi, Jang-Hwan [Department of Radiology, Stanford University, Stanford, California 94305 and Department of Mechanical Engineering, Stanford University, Stanford, California 94305 (United States)] [Department of Radiology, Stanford University, Stanford, California 94305 and Department of Mechanical Engineering, Stanford University, Stanford, California 94305 (United States); Maier, Andreas; Keil, Andreas; McWalter, Emily J.; Gold, Garry E.; Fahrig, Rebecca [Department of Radiology, Stanford University, Stanford, California 94305 (United States)] [Department of Radiology, Stanford University, Stanford, California 94305 (United States); Pal, Saikat [Biomedical Engineering Department, California Polytechnic State University, San Luis Obispo, California 93407 (United States)] [Biomedical Engineering Department, California Polytechnic State University, San Luis Obispo, California 93407 (United States); Beaupré, Gary S. [Musculoskeletal Research Laboratory, VA Palo Alto Health Care System, Palo Alto, California 94304 (United States)] [Musculoskeletal Research Laboratory, VA Palo Alto Health Care System, Palo Alto, California 94304 (United States)

2014-06-15

113

Expressing gait-line symmetry in able-bodied gait  

PubMed Central

Background Gait-lines, or the co-ordinates of the progression of the point of application of the vertical ground reaction force, are a commonly reported parameter in most in-sole measuring systems. However, little is known about what is considered a "normal" or "abnormal" gait-line pattern or level of asymmetry. Furthermore, no reference databases on healthy young populations are available for this parameter. Thus the aim of this study is to provide such reference data in order to allow this tool to be better used in gait analysis. Methods Vertical ground reaction force data during several continuous gait cycles were collected using a Computer Dyno Graphy in-sole system® for 77 healthy young able-bodied subjects. A curve (termed gait-line) was obtained from the co-ordinates of the progression of the point of application of the force. An Asymmetry Coefficient Curve (AsC) was calculated between the mean gait-lines for the left and right foot for each subject. AsC limits of ± 1.96 and 3 standard deviations (SD) from the mean were then calculated. Gait-line data from 5 individual subjects displaying pathological gait due to disorders relating to the discopathy of the lumbar spine (three with considerable plantarflexor weakness, two with considerable dorsiflexor weakness) were compared to the AsC results from the able-bodied group. Results The ± 1.96 SD limit suggested that non-pathological gait falls within 12–16% asymmetry for gait-lines. Those exhibiting pathological gait fell outside both the ± 1.96 and ± 3SD limits at several points during stance. The subjects exhibiting considerable plantarflexor weakness all fell outside the ± 1.96SD limit from 30–50% of foot length to toe-off while those exhibiting considerable dorsiflexor weakness fell outside the ± 1.96SD limit between initial contact to 25–40% of foot length, and then surpassed the ± 3SD limit after 55–80% of foot length. Conclusion This analysis of gait-line asymmetry provides a reference database for young, healthy able-bodied subject populations for both further research and clinical gait analysis. This information is used to suggest non-pathological gait-line asymmetry pattern limits, and limits where detailed case analysis is warranted. PMID:19099568

Jele?, Piotr; Wit, Andrzej; Dudzi?ski, Krzysztof; Nolan, Lee

2008-01-01

114

Lateral balance control for robotic gait training.  

PubMed

For the rehabilitation of neurological patients robot-aided gait training is increasingly being used. Lack of balance training in these robotic gait trainers might contribute to the fact that they do not live up to the expectations. Therefore, in this study we developed and evaluated an algorithm to support lateral balance during walking, through controlling pelvis motions. This algorithm assists the pelvis, according to a natural pelvic sway pattern, rather than attracting it to the middle of the treadmill. The support algorithm was tested on six healthy young subjects who walked on a treadmill, while different support gains were introduced. Using a higher support gain resulted in a closer approximation of the pelvic sway towards the reference pattern. Step width and step width variability reduced when the external stabilization was provided, and the stability margin increased. This indicates that artificial stabilization reduces the need for active lateral balance control. The presented algorithm to support lateral balance provides a way to assist balance in a more physiological way, compared to attracting the subject to the centre of the treadmill. Here the user is attracted/assisted towards a more natural weight shift pattern. This also facilitates a more natural input of the load receptors, which are largely involved in the regulation of muscle activation patterns and the transitions between the different gait phases. PMID:24187182

Koopman, B; Meuleman, J H; van Asseldonk, E H F; van der Kooij, H

2013-06-01

115

Upper limb loadings of gait with crutches.  

PubMed

Long-term crutch users and patients with arthritis are particularly susceptible to upper limb joint degeneration during aided gait. The function of the walking aid for stability, support, and restraint/propulsion must be optimized with the upper limb loadings caused by the aids. Post-operative total hip replacement (THR) patients, tibial fracture, and paraplegic subjects using sticks and elbow crutches were analyzed in this study. Elbow and shoulder joint centers and aid orientations were monitored simultaneously in three dimensions and combined with aid forces to determine upper limb moment loadings. Three loading effects were observed: tendency for the aids to cause 1) the elbow to flex and shoulder to extend, 2) the elbow and shoulder to extend, and 3) the shoulder to abduct. Moment values of up to 0.10 Nm per body weight (BW) causing the shoulder to extend were measured, i.e., of similar magnitude to the moments at the hip in unaided gait. A modification of the elbow crutch, designed to improve medial-lateral stability, was unsuccessful in use due to wrist instability. This reinforced the requirement that crutch designs integrate the aid's function in gait with the ability of the upper limb joints to balance the applied loads. PMID:3695427

Opila, K A; Nicol, A C; Paul, J P

1987-11-01

116

Gait recognition and walking exercise intensity estimation.  

PubMed

Cardiovascular patients consult doctors for advice regarding regular exercise, whereas obese patients must self-manage their weight. Because a system for permanently monitoring and tracking patients' exercise intensities and workouts is necessary, a system for recognizing gait and estimating walking exercise intensity was proposed. For gait recognition analysis, ?? filters were used to improve the recognition of athletic attitude. Furthermore, empirical mode decomposition (EMD) was used to filter the noise of patients' attitude to acquire the Fourier transform energy spectrum. Linear discriminant analysis was then applied to this energy spectrum for training and recognition. When the gait or motion was recognized, the walking exercise intensity was estimated. In addition, this study addressed the correlation between inertia and exercise intensity by using the residual function of the EMD and quadratic approximation to filter the effect of the baseline drift integral of the acceleration sensor. The increase in the determination coefficient of the regression equation from 0.55 to 0.81 proved that the accuracy of the method for estimating walking exercise intensity proposed by Kurihara was improved in this study. PMID:24714057

Lin, Bor-Shing; Liu, Yu-Ting; Yu, Chu; Jan, Gene Eu; Hsiao, Bo-Tang

2014-04-01

117

Gait Recognition and Walking Exercise Intensity Estimation  

PubMed Central

Cardiovascular patients consult doctors for advice regarding regular exercise, whereas obese patients must self-manage their weight. Because a system for permanently monitoring and tracking patients’ exercise intensities and workouts is necessary, a system for recognizing gait and estimating walking exercise intensity was proposed. For gait recognition analysis, ?? filters were used to improve the recognition of athletic attitude. Furthermore, empirical mode decomposition (EMD) was used to filter the noise of patients’ attitude to acquire the Fourier transform energy spectrum. Linear discriminant analysis was then applied to this energy spectrum for training and recognition. When the gait or motion was recognized, the walking exercise intensity was estimated. In addition, this study addressed the correlation between inertia and exercise intensity by using the residual function of the EMD and quadratic approximation to filter the effect of the baseline drift integral of the acceleration sensor. The increase in the determination coefficient of the regression equation from 0.55 to 0.81 proved that the accuracy of the method for estimating walking exercise intensity proposed by Kurihara was improved in this study. PMID:24714057

Lin, Bor-Shing; Liu, Yu-Ting; Yu, Chu; Jan, Gene Eu; Hsiao, Bo-Tang

2014-01-01

118

Increasing weight-bearing physical activity and calcium-rich foods to promote bone mass gains among 9–11 year old girls: outcomes of the Cal-Girls study  

PubMed Central

Background A two-year, community-based, group-randomized trial to promote bone mass gains among 9–11 year-old girls through increased intake of calcium-rich foods and weight-bearing physical activity was evaluated. Methods Following baseline data collection, 30 5th-grade Girl Scout troops were randomized to a two-year behavioral intervention program or to a no-treatment control group. Evaluations were conducted at baseline, one year, and two years. Measures included bone mineral content, density, and area (measured by DXA), dietary calcium intake (24-hour recall), and weight-bearing physical activity (physical activity checklist interview). Mixed-model regression was used to evaluate treatment-related changes in bone mineral content (g) for the total body, lumbar spine (L1-L4), proximal femur, one-third distal radius, and femoral neck. Changes in eating and physical activity behavioral outcomes were examined. Results Although the intervention was implemented with high fidelity, no significant intervention effects were observed for total bone mineral content or any specific bone sites. Significant intervention effects were observed for increases in dietary calcium. No significant intervention effects were observed for increases in weight-bearing physical activity. Conclusion Future research needs to identify the optimal dosage of weight-bearing physical activity and calcium-rich dietary behavior change required to maximize bone mass gains in pre-adolescent and adolescent girls. PMID:16029507

French, Simone A; Story, Mary; Fulkerson, Jayne A; Himes, John H; Hannan, Peter; Neumark-Sztainer, Dianne; Ensrud, Kristine

2005-01-01

119

Gait festination in Parkinson's disease  

Microsoft Academic Search

Background: Festinating gait (FSG) was first associated with parkinsonism by Sir James Parkinson, in his original essay on “The Shaking Palsy”. Its frequency and relation to other parkinsonian features have never been assessed.Objective: To study the relationships between gait festination and other parkinsonian clinical features among patients with Parkinson's disease (PD).Method: During an open lecture to patients with PD who

N Giladi; H Shabtai; E Rozenberg; E Shabtai

2001-01-01

120

Geometric moments for gait description  

NASA Astrophysics Data System (ADS)

The optical flow associated with a set of digital images of a moving individual is analyzed in order to extract a gait signature. For this, invariant Hu moments are obtained for image description. A Hu Moment History (HMH) is obtained from K frames to describe the gait signature of individuals in a video. The gait descriptors are subsequences of the HMH of variable width. Each subsequence is generated by means of genetic algorithms and used for classification in a neuronal network. The database for algorithm evaluation is MoBo, and the gait classification results are above 90% for the cases of slow and fast walking and 100% for the cases of walking with a ball and inclined walking. An optical processor is also implemented in order to obtain the descriptors of the human gait.

Toxqui-Quitl, C.; Morales-Batalla, V.; Padilla-Vivanco, A.; Camacho-Bello, C.

2013-09-01

121

Gait termination: a review of experimental methods and the effects of ageing and gait pathologies  

Microsoft Academic Search

The study of human gait has expanded and diversified to the extent that it is now possible to identify a substantive literature concerning a variety of gait tasks, such as gait initiation [Halliday SE, Winter DA, Frank JS, Patla AE, Prince F. The initiation of gait in young, elderly, and Parkinson's disease subjects. Gait Posture 1998;8:8–14; Mickelborough J, van der

W. A. Sparrow; Oren Tirosh

2005-01-01

122

Pedicle digital pad transfer and negative pressure wound therapy for reconstruction of the weight-bearing surface after complete digital loss in a dog.  

PubMed

A young Labrador Retriever was presented for treatment of severe distal hindlimb necrosis caused by bandage ischemia. During digit amputation at the metatarsophalangeal joints, the third and fourth digital pads were salvaged and transferred to the metatarsal stump to create a weight-bearing surface. Negative pressure wound therapy (NPWT) was utilized for flap immobilization and to promote granulation tissue in the remaining wound defect. Sturdy adherence of the digital pads was achieved after only four days. The skin defect healed completely by second intention and the stump was epithelialized with a thin pad after three months. At the nine month follow-up examination, the stump had a thick hyperkeratinized pad. The dog walked and ran without any apparent signs of discomfort and compensated for the loss of limb length by extending the stifle and tarsocrural joints. Despite a challenging wound in a difficult anatomical location, digital pad flap transfer and NPWT proved successful in restoring long-term ambulation in an active large breed dog. PMID:25449188

Or, M; Van Goethem, B; Polis, I; Spillebeen, A; Vandekerckhove, P; Saunders, J; de Rooster, H

2014-12-01

123

Design of a mobile gait monitoring system  

Microsoft Academic Search

In this paper, a mobile gait monitoring system (MGMS) is proposed for the diagnosis of abnormal gait and rehabilitation. The proposed MGMS consists of Smart Shoes and a micro signal processor with a touch screen display. It monitors patients' gait by observing the ground contact forces (GCFs) and the center of GCF (CoGCF). Since visual feedback about patients' gait and

Joonbum Bae; Kyoungchul Kong; Masayoshi Tomizuka

2010-01-01

124

Intoeing gait in children.  

PubMed

OBJECTIVE: To review the aetiology and management of intoeing. DATA SOURCES: Medline and non-Medline literature search, and personal experience. STUDY SELECTION: Studies that provided evidence-based information about the aetiology and management of paediatric intoeing gait were selected. DATA EXTRACTION: Data were extracted and reviewed independently by both authors. DATA SYNTHESIS: An intoeing gait affects many children and, as with flexible flatfoot, bowleg, and knock-knee, it falls into the category of physiological problems that occur in normal children. The usual causes are excessive femoral anteversion, internal tibial torsion, and metatarsus adductus. Management is based on understanding the causes and the natural course of the condition and the effectiveness of various treatment modalities. Unfortunately, due to poor understanding of the condition, intoeing is commonly overtreated with braces or special footwear. CONCLUSIONS: Intoeing is one of the most common conditions encountered in paediatric orthopaedic practice. It is important to make an early diagnosis of pathological causes of intoeing such as cerebral palsy and developmental dysplasia of the hips so that treatment can be commenced as soon as possible. PMID:10870163

Li; Leong

1999-12-01

125

Support vector machines for automated gait classification  

Microsoft Academic Search

Ageing influences gait patterns causing constant threats to control of locomotor balance. Automated recognition of gait changes has many advantages including, early identification of at-risk gait and monitoring the progress of treatment outcomes. In this paper, we apply an artificial intelligence technique [support vector machines (SVM)] for the automatic recognition of young-old gait types from their respective gait-patterns. Minimum foot

Rezaul K. Begg; Marimuthu Palaniswami; Brendan Owen

2005-01-01

126

Polar Bears  

NSDL National Science Digital Library

Use the following websites to answer questions about the rapid disappearance of polar bears in the Arctic region. Polar Bear picture Polar Bear Tracker 1: What region in the world has the fewest polar bears? 2: Using the internet as a resource, provide some reasons as to why this region is suffering from the most polar bear differences? Polar Bears Change Diet 1: Why are polar bears having to change their diets? 2: List some other factors (besides diet) in the ...

Thomas, Mr.

2010-09-27

127

Bearing system  

DOEpatents

A bearing system includes backup bearings for supporting a rotating shaft upon failure of primary bearings. In the preferred embodiment, the backup bearings are rolling element bearings having their rolling elements disposed out of contact with their associated respective inner races during normal functioning of the primary bearings. Displacement detection sensors are provided for detecting displacement of the shaft upon failure of the primary bearings. Upon detection of the failure of the primary bearings, the rolling elements and inner races of the backup bearings are brought into mutual contact by axial displacement of the shaft.

Kapich, Davorin D. (Carlsbad, CA)

1987-01-01

128

Simulations of skin and subcutaneous tissue loading in the buttocks while regaining weight-bearing after a push-up in wheelchair users.  

PubMed

Pressure ulcers (PUs) are common in patients who chronically depend on a wheelchair for mobility, such as those with a spinal cord injury (SCI). In attempt to prevent the formation of PUs, pressure relieving maneuvers, such as push-ups, are commonly recommended for individuals with SCI. However, very little is known about skin and subcutaneous fat tissue load distributions during sitting and in particular their development during the process of regaining weight-bearing after a push-up. Knowledge on how these loads evolve during sitting-down is critical for understanding the susceptibility of skin to PUs. Considering the potential practical implications on guidelines for wheelchair users, we studied herein the build-up of shear loads in skin and subcutaneous fat using a model of the buttocks of a single SCI subject. Using 12 variants of our finite element (FE) model, we determined the shear loads in skin and subcutaneous fat tissues under the ischial tuberosities when sitting down on foam cushions with different stiffness properties, in healthy skin and scarred skin conditions, focusing on the time course of the build-up of tissue loads. We found substantial differences between the loading curves of skin and fat: While the fat was loaded at a nearly constant rate, skin loads increased nonlinearly - with a greater load/time slope at early skin-support contact. In the context of tissue health and prevention of PUs, this indicates that the more sensitive period with respect to skin integrity is at initial skin-support contact. We further found that the edges of a pre-existing scar are more susceptible to injury, and the greater risk for that is when a hypertrophic scar is present. Despite that this is a theoretical modeling study with associated limitations, we believe that it is already appropriate to recommend to patients to reposition themselves gradually and gently, and not to "fall" back into the wheelchair after finishing a push-up maneuver. PMID:23706990

Levy, Ayelet; Kopplin, Kara; Gefen, Amit

2013-12-01

129

High frequency circular translation pin-on-disk method for accelerated wear testing of ultrahigh molecular weight polyethylene as a bearing material in total hip arthroplasty.  

PubMed

The temporal change of the direction of sliding relative to the ultrahigh molecular weight polyethylene (UHMWPE) component of prosthetic joints is known to be of crucial importance with respect to wear. One complete revolution of the resultant friction vector is commonly called a wear cycle. It was hypothesized that in order to accelerate the wear test, the cycle frequency may be substantially increased if the circumference of the slide track is reduced in proportion, and still the wear mechanisms remain realistic and no overheating takes place. This requires an additional slow motion mechanism with which the lubrication of the contact is maintained and wear particles are conveyed away from the contact. A three-station, dual motion high frequency circular translation pin-on-disk (HF-CTPOD) device with a relative cycle frequency of 25.3Hz and an average sliding velocity of 27.4mm/s was designed. The pins circularly translated at high frequency (1.0mm per cycle, 24.8Hz, clockwise), and the disks at low frequency (31.4mm per cycle, 0.5Hz, counter-clockwise). In a 22 million cycle (10 day) test, the wear rate of conventional gamma-sterilized UHMWPE pins against polished CoCr disks in diluted serum was 1.8mg per 24h, which was six times higher than that in the established 1Hz CTPOD device. The wear mechanisms were similar. Burnishing of the pin was the predominant feature. No overheating took place. With the dual motion HF-CTPOD method, the wear testing of UHMWPE as a bearing material in total hip arthroplasty can be substantially accelerated without concerns of the validity of the wear simulation. PMID:25498368

Saikko, Vesa

2015-01-21

130

Weight-Bearing MR Imaging as an Option in the Study of Gravitational Effects on the Vocal Tract of Untrained Subjects in Singing Phonation  

PubMed Central

Magnetic Resonance Imaging (MRI) of subjects in a supine position can be used to evaluate the configuration of the vocal tract during phonation. However, studies of speech phonation have shown that gravity can affect vocal tract shape and bias measurements. This is one of the reasons that MRI studies of singing phonation have used professionally trained singers as subjects, because they are generally considered to be less affected by the supine body position and environmental distractions. A study of untrained singers might not only contribute to the understanding of intuitive singing function and aid the evaluation of potential hazards for vocal health, but also provide insights into the effect of the supine position on singers in general. In the present study, an open configuration 0.25 T MRI system with a rotatable examination bed was used to study the effect of body position in 20 vocally untrained subjects. The subjects were asked to sing sustained tones in both supine and upright body positions on different pitches and in different register conditions. Morphometric measurements were taken from the acquired images of a sagittal slice depicting the vocal tract. The analysis concerning the vocal tract configuration in the two body positions revealed differences in 5 out of 10 measured articulatory parameters. In the upright position the jaw was less protruded, the uvula was elongated, the larynx more tilted and the tongue was positioned more to the front of the mouth than in the supine position. The findings presented are in agreement with several studies on gravitational effects in speech phonation, but contrast with the results of a previous study on professional singers of our group where only minor differences between upright and supine body posture were observed. The present study demonstrates that imaging of the vocal tract using weight-bearing MR imaging is a feasible tool for the study of sustained phonation in singing for vocally untrained subjects. PMID:25379885

Traser, Louisa; Burdumy, Michael; Richter, Bernhard; Vicari, Marco; Echternach, Matthias

2014-01-01

131

A robot for gait rehabilitation  

E-print Network

After a stroke, persons suffer from neurological impairments that affect gait, and so require rehabilitation to regain ambulatory function. While 82% of patients recover the ability to walk, current methods including ...

Roberts, Michael (Michael Henry), 1980-

2004-01-01

132

Muscle activity of the gluteus medius at different gait speeds.  

PubMed

[Purpose] The present study aimed to determine the changes in the muscle activities of the gluteus medius, latissimus dorsi, and gluteus maximus at different gait speeds, to collect basic data for the study of the gluteus medius. [Subjects and Methods] The subjects were 18 young and healthy male adults whose mean age, height, and weight were 26.4?years, 173.37?cm, and 72.5?kg, respectively. Electromyograpy was used to measure the maximum voluntary isometric contraction of each muscle three times and the values averaged. Then, the subjects walked on a treadmill at gait speeds of 1.5 m/s, 2.5 m/s, and 3.5 m/s and the muscle activity of each muscle was measured. [Results] The gluteus medius showed no significant difference in muscle activity among the different gait speeds. [Conclusion] For selectively strengthening the gluteus medius, to establish the external stability of the pelvis during walking, weight loading or sloped treadmills are effective interventions. However, different gait speeds exert no significant effect on the selective strengthening of the gluteus medius. PMID:25540497

Lee, Su-Kyoung; Lee, Sang-Yeol; Jung, Jae-Min

2014-12-01

133

Muscle Activity of the Gluteus Medius at Different Gait Speeds  

PubMed Central

[Purpose] The present study aimed to determine the changes in the muscle activities of the gluteus medius, latissimus dorsi, and gluteus maximus at different gait speeds, to collect basic data for the study of the gluteus medius. [Subjects and Methods] The subjects were 18 young and healthy male adults whose mean age, height, and weight were 26.4?years, 173.37?cm, and 72.5?kg, respectively. Electromyograpy was used to measure the maximum voluntary isometric contraction of each muscle three times and the values averaged. Then, the subjects walked on a treadmill at gait speeds of 1.5 m/s, 2.5 m/s, and 3.5 m/s and the muscle activity of each muscle was measured. [Results] The gluteus medius showed no significant difference in muscle activity among the different gait speeds. [Conclusion] For selectively strengthening the gluteus medius, to establish the external stability of the pelvis during walking, weight loading or sloped treadmills are effective interventions. However, different gait speeds exert no significant effect on the selective strengthening of the gluteus medius.

Lee, Su-Kyoung; Lee, Sang-Yeol; Jung, Jae-Min

2014-01-01

134

Quadruped free gait generation combined with body trajectory planning  

Microsoft Academic Search

A method of free gait generation for both straight line and circular body trajectories is proposed utilizing the primary\\/secondary gait. The primary gait is a fixed sequence of leg transfers with modified legend kinematic limits according to the obstacle presence, while the secondary gait is a flexible gait which is generated to adjust the leg-end position. The primary gait is

Shaoping Bait; K. H. Lowt; Teresa Zielinska

1999-01-01

135

KineAssist: a robotic overground gait and balance training device  

Microsoft Academic Search

The KineAssist is a robotic device for gait and balance training. A user-needs analysis led us to focus on increasing the level of challenge to a patient's ability to maintain balance during gait training, and also on maintaining direct involvement of a physical therapist (rather than attempting robotic replacement.) The KineAssist provides partial body weight support and postural torques on

Michael Peshkin; David A. Brown; Julio J. Santos-Munné; Alex Makhlin; Ela Lewis; J. Edward Colgate; James Patton; Doug Schwandt

2005-01-01

136

Polar Bear Polar Bear  

NSDL National Science Digital Library

In this lesson, students will listen for key details in a nonfiction text about polar bears. They will work at completing a graphic organizer with the teacher to help organize their thinking and understanding of key details about a text. They will also complete an independent assignment where they will draw or write two things that they learned about the topic.

Burgess, Kelly

2012-09-11

137

Arthrodesis of the first metatarsal-phalangeal joint with flexible, ridged titanium intramedullary nails alone or supplemented with static staples and immediate weight bearing: a consecutive series of 148 procedures.  

PubMed

Myriad forms of fixation have been proposed for arthrodesis of the first metatarsal-phalangeal joint (MTPJ). However, nonunion of the arthrodesis site remains a common complication. The authors performed a retrospective review of all patients undergoing arthrodesis of the first MTPJ with flexible titanium intramedullary nails alone or supplemented with static staples followed by immediate protected weight bearing. Subjects were included if they had surgery performed only by one of us; not undergone bilateral surgery in the same setting; surgery for pathology of the first MTPJ other than rheumatoid arthritis; weight-bearing preoperative radiographs; postoperative weight-bearing radiographs demonstrating presence or absence of union at the arthrodesis site; initiated weight bearing on the operative foot immediately postoperative in a protective shoe; and documentation of any complications. A total of 128 patients (148 feet) met inclusion criteria and were included. There were 110 (85.9%) females and 18 (14.1%) males with a mean age ± SD of 64 ± 14.1 years. Indications included (a) 93 (62.8%) severe hallux valgus deformity, (b) 37 (25%) hallux rigidus, and (c) 18 (12.2%) failed first MTPJ surgeries. Ten different configurations where included based on the requirements needed to achieve a solid construct intraoperatively. There were a total of 9 (6.1%) complications consisting of 4 (2.7%) asymptomatic nonunions, 4 (2.7%) hardware removals, and 1 (0.7%) loss of reduction requiring revision surgery. The incidence of nonunion with flexible titanium intramedullary nails alone or supplemented with static staples followed by immediate protected weight bearing for predominantly severe hallux valgus and hallux rigidus is lower than the historic mean for most other fixation techniques. However, there is still a need for methodologically sound prospective cohort studies that focus on the use of isolated arthrodesis of the first MTPJ for purely severe hallux valgus or hallux rigidus, and comparison of the technique presented here with other modern osteosynthesis techniques. Levels of Evidence : Therapeutic, Level IV. PMID:22134438

Roukis, Thomas S; Meusnier, Tristan; Augoyard, Marc

2012-02-01

138

Gait assessment in unicompartmental knee arthroplasty patients: Principal component modelling of gait waveforms and clinical status  

Microsoft Academic Search

The reduction and analysis of gait waveform data is a significant barrier to the clinical application of gait analysis. Principal component modelling of gait waveform data reduced the waveform data to measures of distance from normal and these distance measures were shown to be sensitive to changes in gait pattern associated with knee osteoarthritis and its treatment by unicompartmental arthroplasty.

Kevin J. Deluzio; Urs P. Wyss; Patrick A. Costigan; Charles Sorbie; Benny Zee

1999-01-01

139

Gait Dynamics for Recognition and Classification  

E-print Network

This paper describes a representation of the dynamics of human walking action for the purpose of person identification and classification by gait appearance. Our gait representation is based on simple features such as ...

Lee, Lily

2001-09-01

140

Gait recognition across various walking speeds using higher order shape configuration based on a differential composition model.  

PubMed

Gait has been known as an effective biometric feature to identify a person at a distance. However, variation of walking speeds may lead to significant changes to human walking patterns. It causes many difficulties for gait recognition. A comprehensive analysis has been carried out in this paper to identify such effects. Based on the analysis, Procrustes shape analysis is adopted for gait signature description and relevant similarity measurement. To tackle the challenges raised by speed change, this paper proposes a higher order shape configuration for gait shape description, which deliberately conserves discriminative information in the gait signatures and is still able to tolerate the varying walking speed. Instead of simply measuring the similarity between two gaits by treating them as two unified objects, a differential composition model (DCM) is constructed. The DCM differentiates the different effects caused by walking speed changes on various human body parts. In the meantime, it also balances well the different discriminabilities of each body part on the overall gait similarity measurements. In this model, the Fisher discriminant ratio is adopted to calculate weights for each body part. Comprehensive experiments based on widely adopted gait databases demonstrate that our proposed method is efficient for cross-speed gait recognition and outperforms other state-of-the-art methods. PMID:22665509

Kusakunniran, Worapan; Wu, Qiang; Zhang, Jian; Li, Hongdong

2012-12-01

141

Bear Scratch  

USGS Multimedia Gallery

When looking for a place to set up a trapping location, scientists look for existing bear sign such as scratches on trees and bear scat. Sometimes traps are set in areas that have no obvious bear sign to determine if indeed bears are present....

142

Gait enhancing mobile shoe (GEMS) for rehabilitation  

Microsoft Academic Search

Individuals with certain types of central nervous system damage, such as stroke, have an asymmetric walking gait. Using a split- belt treadmill, where each leg walks at a different speed, has been shown to help rehabilitate walking impaired individuals, but there is one distinct drawback; the corrected gait does not transfer well to walking over ground. To increase the gait

Allison de Groot; Ryan Decker; Kyle B. Reed

2009-01-01

143

Gait Recognition using Dynamic Affine Invariants  

Microsoft Academic Search

We present a method for recognizing classes of human gaits from video sequences. We propose a novel image based representation for human gaits. At any instance of time a gait is represented by a vector of affine invariant moments. The invariants are computed on the binary silhouettes cor- responding to the moving body. We represent the time tra- jectories of

Alessandro Bissacco; Payam Saisan; Stefano Soatto

2004-01-01

144

Gait Stability in Children with Cerebral Palsy  

ERIC Educational Resources Information Center

Children with unilateral Cerebral Palsy (CP) have several gait impairments, amongst which impaired gait stability may be one. We tested whether a newly developed stability measure (the foot placement estimator, FPE) which does not require long data series, can be used to asses gait stability in typically developing (TD) children as well as…

Bruijn, Sjoerd M.; Millard, Matthew; van Gestel, Leen; Meyns, Pieter; Jonkers, Ilse; Desloovere, Kaat

2013-01-01

145

Gait estimation using foot-pressure sensors  

Microsoft Academic Search

Along with the progress of elderly society, gait is increasingly important to live an independent life. Therefore, simple evaluation and analysis of gait is necessary. Our final goal is to propose a wearable gait analytical device. As described herein, we have estimated the floor reaction force vector using thin sensors. The floor reaction force vector during walking is the direction

K. M. Waki; T. Iwam; T. Matsunaga; Y. Shimada; G. Obinata

2009-01-01

146

Gait Apraxia: Further Clues to Localization  

Microsoft Academic Search

Background\\/Aims: Gait apraxia characterized primarily by gait ignition failure has been linked to lesions involving the dorsomedial frontal lobes, but the precise locus within this general region has not been determined. It has previously been hypothesized by Thompson and Marsden that disease, disconnection, or dysfunction of supplementary motor area (SMA) may account for the similarities in the gait disorders observed

Stephen E. Nadeau

2007-01-01

147

A mechanical energy analysis of gait initiation  

NASA Technical Reports Server (NTRS)

The analysis of gait initiation (the transient state between standing and walking) is an important diagnostic tool to study pathologic gait and to evaluate prosthetic devices. While past studies have quantified mechanical energy of the body during steady-state gait, to date no one has computed the mechanical energy of the body during gait initiation. In this study, gait initiation in seven normal male subjects was studied using a mechanical energy analysis to compute total body energy. The data showed three separate states: quiet standing, gait initiation, and steady-state gait. During gait initiation, the trends in the energy data for the individual segments were similar to those seen during steady-state gait (and in Winter DA, Quanbury AO, Reimer GD. Analysis of instantaneous energy of normal gait. J Biochem 1976;9:253-257), but diminished in amplitude. However, these amplitudes increased to those seen in steady-state during the gait initiation event (GIE), with the greatest increase occurring in the second step due to the push-off of the foundation leg. The baseline level of mechanical energy was due to the potential energy of the individual segments, while the cyclic nature of the data was indicative of the kinetic energy of the particular leg in swing phase during that step. The data presented showed differences in energy trends during gait initiation from those of steady state, thereby demonstrating the importance of this event in the study of locomotion.

Miller, C. A.; Verstraete, M. C.

1999-01-01

148

Limbless Conforming Gaits with Modular Robots  

Microsoft Academic Search

This paper presents experimentation using the PolyBot modular robot of two limbless gaits which conform to environment. A conforming loop gait is low profile and traverses over a variety of obstacles where the ratio of the height of the obstacle to robot is up to 1.3. A concertina snake gait is capable of negotiating narrow passages (for example a width

Mark Yim; Craig Eldershaw; Ying Zhang; David Duff

2004-01-01

149

Optimal Gait Analysis of Snake Robot Dynamics  

Microsoft Academic Search

Though there have been a lot of research in the area of snake-robot kinematics and dynamics, a little attention has been given to flnd out an optimal gait for the robot. This optimal gait until now is being calculated using a graphical method. An attempt, here, is made to get these optimum gait parameters using evolutionary algorithms. We intend to

Vipul Mehta

150

Gait and jump analysis in healthy cats using a pressure mat system.  

PubMed

Physical orthopaedic examination in cats does not always reveal signs of lameness and no objective gait analysis method has yet been standardised for use in cats. The aims of the present study were to define appropriate parameters for pressure mat analyses during walk and jump, and to define reference values for gait parameters of healthy cats. Further, the distribution of the vertical force within the paws and the influence of a non-centred head position were investigated. The hypothesis was that cats have a symmetrical gait, a front/hindlimb asymmetry similar to dogs, and that peak vertical force (PVF) and vertical impulse (VI) have high intraclass correlation coefficients, confirming the reliability of these parameters. Data for walking (n = 46) showed gait symmetry indices of close to 1.0, besides PVF front/hind (1.3 ± 0.2). The PVF front/hind for jumping cats (n = 16) was 1.7 ± 0.6. Results from the distribution of the vertical force within the paw (n = 39) showed that the main weight during a strike is transferred from the caudal towards the craniomedial part of the paw. The findings support the hypothesis that healthy cats have similar gait symmetry to healthy dogs and that PVF and VI are reliable gait parameters. In conclusion, the present study provides a reference range for healthy cats. Further studies are needed to investigate gait parameters in cats with orthopaedic disease. PMID:25239912

Stadig, Sarah M; Bergh, Anna K

2014-09-19

151

Biomechanics of Gait during Pregnancy  

PubMed Central

Introduction. During pregnancy women experience several changes in the body's physiology, morphology, and hormonal system. These changes may affect the balance and body stability and can cause discomfort and pain. The adaptations of the musculoskeletal system due to morphological changes during pregnancy are not fully understood. Few studies clarify the biomechanical changes of gait that occur during pregnancy and in postpartum period. Purposes. The purpose of this review was to analyze the available evidence on the biomechanical adaptations of gait that occur throughout pregnancy and in postpartum period, specifically with regard to the temporal, spatial, kinematic, and kinetic parameters of gait. Methods. Three databases were searched and 9 studies with a follow-up design were retrieved for analysis. Results. Most studies performed temporal, spatial, and kinematic analysis. Only three studies performed kinetic analysis. Conclusion. The adaptation strategies to the anatomical and physiological changes throughout pregnancy are still unclear, particularly in a longitudinal perspective and regarding kinetic parameters. PMID:25587566

Vieira, Filomena

2014-01-01

152

Human gait recognition via deterministic learning.  

PubMed

Recognition of temporal/dynamical patterns is among the most difficult pattern recognition tasks. Human gait recognition is a typical difficulty in the area of dynamical pattern recognition. It classifies and identifies individuals by their time-varying gait signature data. Recently, a new dynamical pattern recognition method based on deterministic learning theory was presented, in which a time-varying dynamical pattern can be effectively represented in a time-invariant manner and can be rapidly recognized. In this paper, we present a new model-based approach for human gait recognition via the aforementioned method, specifically for recognizing people by gait. The approach consists of two phases: a training (learning) phase and a test (recognition) phase. In the training phase, side silhouette lower limb joint angles and angular velocities are selected as gait features. A five-link biped model for human gait locomotion is employed to demonstrate that functions containing joint angle and angular velocity state vectors characterize the gait system dynamics. Due to the quasi-periodic and symmetrical characteristics of human gait, the gait system dynamics can be simplified to be described by functions of joint angles and angular velocities of one side of the human body, thus the feature dimension is effectively reduced. Locally-accurate identification of the gait system dynamics is achieved by using radial basis function (RBF) neural networks (NNs) through deterministic learning. The obtained knowledge of the approximated gait system dynamics is stored in constant RBF networks. A gait signature is then derived from the extracted gait system dynamics along the phase portrait of joint angles versus angular velocities. A bank of estimators is constructed using constant RBF networks to represent the training gait patterns. In the test phase, by comparing the set of estimators with the test gait pattern, a set of recognition errors are generated, and the average L(1) norms of the errors are taken as the similarity measure between the dynamics of the training gait patterns and the dynamics of the test gait pattern. Therefore, the test gait pattern similar to one of the training gait patterns can be rapidly recognized according to the smallest error principle. Finally, experiments are carried out on the NLPR and UCSD gait databases to demonstrate the effectiveness of the proposed approach. PMID:22982093

Zeng, Wei; Wang, Cong

2012-11-01

153

Fiducial marker-based correction for involuntary motion in weight-bearing C-arm CT scanning of knees. Part I. Numerical model-based optimization  

PubMed Central

Purpose: Human subjects in standing positions are apt to show much more involuntary motion than in supine positions. The authors aimed to simulate a complicated realistic lower body movement using the four-dimensional (4D) digital extended cardiac-torso (XCAT) phantom. The authors also investigated fiducial marker-based motion compensation methods in two-dimensional (2D) and three-dimensional (3D) space. The level of involuntary movement-induced artifacts and image quality improvement were investigated after applying each method. Methods: An optical tracking system with eight cameras and seven retroreflective markers enabled us to track involuntary motion of the lower body of nine healthy subjects holding a squat position at 60° of flexion. The XCAT-based knee model was developed using the 4D XCAT phantom and the optical tracking data acquired at 120 Hz. The authors divided the lower body in the XCAT into six parts and applied unique affine transforms to each so that the motion (6 degrees of freedom) could be synchronized with the optical markers’ location at each time frame. The control points of the XCAT were tessellated into triangles and 248 projection images were created based on intersections of each ray and monochromatic absorption. The tracking data sets with the largest motion (Subject 2) and the smallest motion (Subject 5) among the nine data sets were used to animate the XCAT knee model. The authors defined eight skin control points well distributed around the knees as pseudo-fiducial markers which functioned as a reference in motion correction. Motion compensation was done in the following ways: (1) simple projection shifting in 2D, (2) deformable projection warping in 2D, and (3) rigid body warping in 3D. Graphics hardware accelerated filtered backprojection was implemented and combined with the three correction methods in order to speed up the simulation process. Correction fidelity was evaluated as a function of number of markers used (4–12) and marker distribution in three scenarios. Results: Average optical-based translational motion for the nine subjects was 2.14 mm (±0.69 mm) and 2.29 mm (±0.63 mm) for the right and left knee, respectively. In the representative central slices of Subject 2, the authors observed 20.30%, 18.30%, and 22.02% improvements in the structural similarity (SSIM) index with 2D shifting, 2D warping, and 3D warping, respectively. The performance of 2D warping improved as the number of markers increased up to 12 while 2D shifting and 3D warping were insensitive to the number of markers used. The minimum required number of markers for 2D shifting, 2D warping, and 3D warping was 4–6, 12, and 8, respectively. An even distribution of markers over the entire field of view provided robust performance for all three correction methods. Conclusions: The authors were able to simulate subject-specific realistic knee movement in weight-bearing positions. This study indicates that involuntary motion can seriously degrade the image quality. The proposed three methods were evaluated with the numerical knee model; 3D warping was shown to outperform the 2D methods. The methods are shown to significantly reduce motion artifacts if an appropriate marker setup is chosen. PMID:24007156

Choi, Jang-Hwan; Fahrig, Rebecca; Keil, Andreas; Besier, Thor F.; Pal, Saikat; McWalter, Emily J.; Beaupré, Gary S.; Maier, Andreas

2013-01-01

154

Nonunion rate of first metatarsal-phalangeal joint arthrodesis for end-stage hallux rigidus with crossed titanium flexible intramedullary nails and dorsal static staple with immediate weight-bearing.  

PubMed

Myriad forms of fixation have been proposed for arthrodesis of the first metatarsal-phalangeal joint (MTPJ). Regardless of the fixation type, nonunion of the arthrodesis site has been purported to be a common complication. We performed a retrospective review of all patients undergoing arthrodesis of the first MTPJ for end-stage hallux rigidus with 2 crossed flexible titanium intramedullary nails and a dorsal static 10-mm titanium staple followed by immediate protected weight-bearing. The inclusion criteria were as follows: the exact internal fixation technique described was employed for end-stage hallux rigidus of the first MTPJ only; preoperative and at least 6 weeks of postoperative weight-bearing radiographs were available; weight-bearing was initiated on the operative foot immediately in a protective shoe; the patient was followed for at least 6 months postoperatively; any complication was documented; and bilateral surgery was not done in the same setting. A total of 42 female patients (51 feet) with a mean age ± SD of 69.4 ± 9.2 years met the inclusion criteria. Complications resulting from technical error during insertion of the crossed titanium flexible intramedullary nails occurred in 3 feet (5.9%), but none led to nonunion or revision surgery. One delayed union (2%) occurred but it ultimately united. The incidence of nonunion after arthrodesis of the first MTPJ consisting of 2 crossed flexible titanium intramedullary nails and a dorsal static 10-mm titanium staple for end-stage hallux rigidus in an exclusively female population was lower than the historic mean for most other fixation techniques. However, methodologically sound prospective cohort studies that focus on the use of isolated arthrodesis of the first MTPJ for end-stage hallux rigidus in both male and female patients are still needed, as are comparisons of the presented technique with other modern osteosynthesis techniques. PMID:22225597

Roukis, Thomas S; Meusnier, Tristan; Augoyard, Marc

2012-01-01

155

Polar Bear  

NSDL National Science Digital Library

This site from the World Wildlife Fund (WWF) International provides general information about polar bears as well as data on the movements of two radio-collared bears, along with the ice status, through a series of online maps.

2007-01-01

156

Identification of humans using gait  

Microsoft Academic Search

We propose a view-based approach to recognize hu- mans from their gait. Two different image features have been con- sidered: the width of the outer contour of the binarized silhouette of the walking person and the entire binary silhouette itself. To ob- tain the observation vector from the image features, we employ two different methods. In the first method, referred

Amit A. Kale; Aravind Sundaresan; A. N. Rajagopalan; Naresh P. Cuntoor; Amit K. Roy-Chowdhury; Volker Krüger; Rama Chellappa

2004-01-01

157

Human Gait Acquisition and Characterization  

Microsoft Academic Search

This paper analyzes human motion, more specifically the human gait in the sagittal plane. A video camera is used to acquire images of a walking person, fitted with a set of white light-emitting diodes (LEDs). The acquired trajectories of the light points are then used to specify joint trajectories in a biped robot. To analyze the stability of the human

João P. Ferreira; Manuel Marques Crisóstomo; A. Paulo Coimbra

2009-01-01

158

The syndrome of senile gait  

Microsoft Academic Search

Infrared computed stroboscopic photometry was used to quantify the kinematic profiles of walking in 10 elderly patients with symmetrical neurological disturbances of gait and in 19 age-matched neurologically healthy people. Clinical examination of the patients revealed similar profiles of walking even though their diagnoses were vascular dementia (2), normal pressure hydrocephalus (2), Alzheimer dementia with possible normal pressure hydrocephalus (2),

Rodger J. Elble; Larry Hughes; Constance Higgins

1992-01-01

159

Testing and Lubrication for Single Race Bearings  

SciTech Connect

Three ES and H-compatible lubricants (Environment, Safety and Health) for single race bearing applications and one hybrid-material single race bearings were evaluated and compared against single race bearings with trichlorotrifluoroethane (Freon) deposition of low molecular weight polytetrafluoroethylene (PTFE) bearing lubricant extracted from Vydax{trademark}. Vydax is a product manufactured by DuPont consisting of various molecular weights of PTFE suspended in trichlorotrifluoroethane (Freon), which is an ozone-depleting solvent. Vydax has been used as a bearing lubricant in stronglink mechanisms since 1974. Hybrid bearings with silicon nitride balls and molded glass-nylon-Teflon retainers, bearings lubricated with titanium carbide (TiC) on the balls, bearings lubricated with sputtered MoS{sub 2} on races and retainers, and bearings lubricated with electrophoretically deposited MoS{sub 2} were evaluated. The bearings were maintained in a preloaded state in bearing cartridges during cycling and vibration tests. Bearings with electrophoretically deposited MoS{sub 2} performed as well as bearings lubricated with Vydax and were the best performing candidate. All candidates were suitable for low preload applications. Bearings with TiC coated balls and bearings lubricated with sputtered MoS{sub 2} on the races and retainers performed well at high preloads, though not as well as bearings lubricated with electrophoretic deposition of MoS{sub 2}. Bearings with silicon nitride balls were not suitable for high preload applications.

Steinhoff, R.G.

1998-03-04

160

The Latest Lessons Learned from Retrieval Analyses of Ultra-High Molecular Weight Polyethylene, Metal-on-Metal, and Alternative Bearing Total Disc Replacements  

PubMed Central

Knowledge regarding the in vivo performance and periposthetic tissue response of cervical and lumbar total disc replacements (TDRs) continues to expand. This review addresses the following four main questions: 1) What are the latest lessons learned from polyethylene in large joints and how are they relevant to current TDRs? 2) What are the latest lessons learned regarding adverse local tissue reactions from metal-on-metal, CoCr bearings in large joints and how are they relevant to current TDRs? 3) What advancements have been made in understanding the in vivo performance of alternative biomaterials, such as stainless steel and polycarbonate urethane, for TDRs in the past five years? 4) How has retrieval analysis of all these various artificial disc bearing technologies advanced the state of the art in preclinical testing of TDRs? The study of explanted artificial discs and their associated tissues can help inform bearing selection as well as the design of future generations of disc arthroplasty. Analyzing retrieved artificial discs is also essential for validating preclinical test methods. PMID:22904606

Kurtz, Steven M.; Toth, Jeffrey M.; Siskey, Ryan; Ciccarelli, Lauren; MacDonald, Dan; Isaza, Jorge; Lanman, Todd; Punt, Ilona; Steinbeck, Marla; Goffin, Jan; van Ooij, André

2012-01-01

161

Optimal Synchronizability of Bearings  

NASA Astrophysics Data System (ADS)

Bearings are mechanical dissipative systems that, when perturbed, relax toward a synchronized (bearing) state. Here we find that bearings can be perceived as physical realizations of complex networks of oscillators with asymmetrically weighted couplings. Accordingly, these networks can exhibit optimal synchronization properties through fine-tuning of the local interaction strength as a function of node degree [Motter, Zhou, and Kurths, Phys. Rev. E 71, 016116 (2005)PLEEE81539-3755]. We show that, in analogy, the synchronizability of bearings can be maximized by counterbalancing the number of contacts and the inertia of their constituting rotor disks through the mass-radius relation, m˜r?, with an optimal exponent ?=?× which converges to unity for a large number of rotors. Under this condition, and regardless of the presence of a long-tailed distribution of disk radii composing the mechanical system, the average participation per disk is maximized and the energy dissipation rate is homogeneously distributed among elementary rotors.

Araújo, N. A. M.; Seybold, H.; Baram, R. M.; Herrmann, H. J.; Andrade, J. S., Jr.

2013-02-01

162

The Inhibition of Subchondral Bone Lesions Significantly Reversed the Weight-Bearing Deficit and the Overexpression of CGRP in DRG Neurons, GFAP and Iba-1 in the Spinal Dorsal Horn in the Monosodium Iodoacetate Induced Model of Osteoarthritis Pain  

PubMed Central

Background Chronic pain is the most prominent and disabling symptom of osteoarthritis (OA). Clinical data suggest that subchondral bone lesions contribute to the occurrence of joint pain. The present study investigated the effect of the inhibition of subchondral bone lesions on joint pain. Methods Osteoarthritic pain was induced by an injection of monosodium iodoacetate (MIA) into the rat knee joint. Zoledronic acid (ZOL), a third generation of bisphosphonate, was used to inhibit subchondral bone lesions. Joint histomorphology was evaluated using X-ray micro computed tomography scanning and hematoxylin-eosin staining. The activity of osteoclast in subchondral bone was evaluated using tartrate-resistant acid phosphatase staining. Joint pain was evaluated using weight-bearing asymmetry, the expression of calcitonin gene-related peptide (CGRP) in the dorsal root ganglion (DRG), and spinal glial activation status using glial fibrillary acidic protein (GFAP) and ionized calcium binding adaptor molecule-1 (Iba-1) immunofluorescence. Afferent neurons in the DRGs that innervated the joints were identified using retrograde fluorogold labeling. Results MIA injections induced significant histomorphological alterations and joint pain. The inhibition of subchondral bone lesions by ZOL significantly reduced the MIA-induced weight-bearing deficit and overexpression of CGRP in DRG neurons, GFAP and Iba-1 in the spinal dorsal horn at 3 and 6 weeks after MIA injection; however, joint swelling and synovial reaction were unaffected. Conclusions The inhibition of subchondral bone lesions alleviated joint pain. Subchondral bone lesions should be a key target in the management of osteoarthritic joint pain. PMID:24204985

Liu, Ming; Zhao, Xin; Wang, Xiaoqing; Li, Yang; Mao, Yuanqing; Zhu, Zhenan

2013-01-01

163

Standardization of kinematic gait measurements and automatic pathological gait pattern diagnostics.  

PubMed

The estimation of patients gait in the field of rehabilitation is the starting point for an appropirate therapy decision and convenient prosthesis or orthosis choice. The measurement and estimation of human locomotion is increasingly being transferred to every day clinical use. In recent times many systems are intended for kinematic gait parameters measurements: stroboscopic photography, movie camera, TV picture analysis, TV signal analysis, chronocyclographical measurement, polarised light goniometer, the "Selspot" system, parallelgram goniometers, exoskeleton goniometers. In the paper the role of the computer in gait measurements is also determined. The problems of the choice of parameters to be measured, unique reference coordinate systems and normal gait pattern are encountered in this work. Finally two versions of pathological gait pattern estimation are described: clinical gait analysis and mathematical quantitative gait analysis. A combination of both methods provides an efficient, compact automatic pathological gait pattern diagnostics. PMID:594692

Stanic, U; Bajd, T; Valencic, V; Kljaji?, M; Acimovi?, R

1977-01-01

164

Aerospace applications of magnetic bearings  

NASA Astrophysics Data System (ADS)

Magnetic bearings have traditionally been considered for use in aerospace applications only where performance advantages have been the primary, if not only, consideration. Conventional wisdom has been that magnetic bearings have certain performance advantages which must be traded off against increased weight, volume, electric power consumption, and system complexity. These perceptions have hampered the use of magnetic bearings in many aerospace applications because weight, volume, and power are almost always primary considerations. This paper will review progress on several active aerospace magnetic bearings programs at SatCon Technology Corporation. The magnetic bearing programs at SatCon cover a broad spectrum of applications including: a magnetically-suspended spacecraft integrated power and attitude control system (IPACS), a magnetically-suspended momentum wheel, magnetic bearings for the gas generator rotor of a turboshaft engine, a vibration-attenuating magnetic bearing system for an airborne telescope, and magnetic bearings for the compressor of a space-rated heat pump system. The emphasis of these programs is to develop magnetic bearing technologies to the point where magnetic bearings can be truly useful, reliable, and well tested components for the aerospace community.

Downer, James; Goldie, James; Gondhalekar, Vijay; Hockney, Richard

1994-05-01

165

Development of hybrid bearing system with thrust superconducting magnetic bearing and radial active electromagnetic bearing  

NASA Astrophysics Data System (ADS)

A superconducting/electromagnetic hybrid bearing system is currently under development and test. This system consists of a thrust superconducting magnetic bearing and a double radial active electromagnetic bearing/motor devices. The thrust bearing has been designed using NdFeB permanent magnets levitating on a set of superconducting monoliths of YBCO, prepared by top seeded melt texturing technique, which supports the weight of the rotor. The bearing/motor devices were conceived as 4-pole 2-phase induction machine using stator windings for delivering torque and radial positioning simultaneously. Using this superconducting axial bearing and the active bearings for the rotor radial positioning, a fully levitating vertical-shaft inductive machine has been tested. The tests were successful in reaching a controlled levitation up to 6,300 rpm.

Nicolsky, R.; Pereira, A. S.; de Andrade, R.; David, D. F. B.; Santisteban, J. A.; Stephan, R. M.; Ripper, A.; Gawalek, W.; Habisreuther, T.; Strasser, T.

166

Human assisted tools for gait analysis and intelligent gait phase detection  

Microsoft Academic Search

Gait analysis is a widely used approach to detect deformations and allow clinicians to conclude possible treatments. However, accurate gait analysis require large amount of data and lengthy assessment times. Therefore this paper presents the initial study of a system which was developed with the intention to provide clinicians a solution to acquire gait parameters and detect anomalies with ease

C. Senanayake; S. M. N. A. Senanayake

2009-01-01

167

Towards a View Invariant Gait Recognition Algorithm  

Microsoft Academic Search

Human gait is a spatio-temporal phenomenon and typifies the motion characteristics of an individual. The gait of a person is easily recognizable when extracted from a side- view of the person. Accordingly, gait-recognition algo- rithms work best when presented with images where the per- son walks parallel to the camera (i.e. the image plane). However, it is not realistic to

Amit A. Kale; Amit K. Roy Chowdhury; Rama Chellappa

2003-01-01

168

Gait dynamics on an inclined walkway  

Microsoft Academic Search

Objective: This paper documents research that quantifies and describes the biomechanics of normal gait on inclined surfaces.Design: Experimental, investigative.Background: It is necessary to walk on inclined surfaces to negotiate the natural and built environments. Little research has been conducted on the biomechanics of normal gait on inclined surfaces.Methods: The gait of 11 healthy male volunteers was measured using a Vicon

Andrew Stuart McIntosh; Karen T. Beatty; Leanne N. Dwan; Deborah R. Vickers

2006-01-01

169

The association between fear of falling and gait variability in both leg and trunk movements.  

PubMed

The aim of this study was to explore whether FoF was associated with variability in both leg and trunk movements during gait in community-dwelling elderly. Ninety-three elderly people participated in this study. Each participant was categorized into either Fear or No-Fear group on the basis of having FoF. The participants walked 15m at their preferred speed. The wireless motion recording sensor units were attached to L3 spinous process and right posterior surface of heel during gait. Gait velocity, stride time and stride length were calculated. Variability in lower limb movements was represented by coefficient of variation (CV) of stride time. Trunk variability was represented by autocorrelation coefficients (AC) in three directions (vertical: VT, mediolateral: ML and anteroposterior: AP), respectively. Gait parameters were compared between groups, and further analyses were performed using generalized linear regression models after adjustment of age, sex, fall experience, height, weight, and gait velocity. Although gait velocity, mean stride time and stride length did not differ significantly between groups, stride time CV and all ACs were significantly worse in the Fear group after adjustment for variables, even including gait velocity (stride time CV: p=0.003, ?=-0.793; AC-VT: p=0.011, ?=0.053; AC-ML: p=0.044, ?=0.075; AC-AP: p=0.002, ?=0.078). Our results suggest that fear of falling is associated with variability in both leg and trunk movements during gait in community-dwelling elderly. Further studies are needed to prove a causal relationship. PMID:24656714

Sawa, Ryuichi; Doi, Takehiko; Misu, Shogo; Tsutsumimoto, Kota; Nakakubo, Sho; Asai, Tsuyoshi; Yamada, Minoru; Ono, Rei

2014-05-01

170

Cerebral Palsy Gait, Clinical Importance  

PubMed Central

ABSTRACT Cerebral palsy refers to a lesion on an immature brain, that determines permanent neurological disorders. Knowing the exact cause of the disease does not alter the treatment management. The etiology is 2-2.5/1000 births and the rate is constant in the last 40-50 years because advances in medical technologies have permitted the survival of smaller and premature new born children. Gait analysis has four directions: kinematics (represents body movements analysis without calculating the forces), kinetics (represents body moments and forces), energy consumption (measured by oximetry), and neuromuscular activity (measured by EMG). Gait analysis can observe specific deviations in a patient, allowing us to be more accurate in motor diagnoses and treatment solutions: surgery intervention, botulinum toxin injection, use of orthosis, physical kinetic therapy, oral medications, baclofen pump. PMID:24790675

TUGUI, Raluca Dana; ANTONESCU, Dinu

2013-01-01

171

Segmentation and classification of gait cycles.  

PubMed

Gait abnormalities can be studied by means of instrumented gait analysis. Foot-switches are useful to study the foot-floor contact and for timing the gait phases in many gait disorders, provided that a reliable foot-switch signal may be collected. Considering long walks allows reducing the intra-subject variability, but requires automatic and user-independent methods to analyze a large number of gait cycles. The aim of this work is to describe and validate an algorithm for the segmentation of the foot-switch signal and the classification of the gait cycles. The performance of the algorithm was assessed comparing its results against the manual segmentation and classification performed by a gait analysis expert on the same signal. The performance was found to be equal to 100% for healthy subjects and over 98% for pathological subjects. The algorithm allows determining the atypical cycles (cycles that do not match the standard sequence of gait phases) for many different kinds of pathological gait, since it is not based on pathology-specific templates. PMID:24760911

Agostini, Valentina; Balestra, Gabriella; Knaflitz, Marco

2014-09-01

172

Regional differences in cortical bone mineral density in the weight-bearing long bone shaft--a pQCT study.  

PubMed

This study used a multislice peripheral quantitative computed tomography (pQCT) to measure volumetric BMD (vBMD) and cortical thickness for investigating regional adaptation in lower tibial shaft in 72 healthy postmenopausal women aged 47-60. Tomographic slices were analysed on four distinct cortical regions: the anterior, posterior, medial and lateral cortical wall. One-way analysis of variance (ANOVA) test was used to compare the vBMD in the four regions. The results showed that the posterior cortex had the highest vBMD (1923 +/- 135.3 mg/cm(3)), significantly (P < 0.001) higher than the anterior cortex (1805 +/- 110.6 mg/cm(3)), medial cortex (1863 +/- 103.6 mg/cm(3)) and lateral cortex (1815 +/- 111.6 mg/cm(3)); whereas there was no significant difference (P > 0.05) between the medial and lateral cortices located near the neutral plane of bending. The anterior cortex had the greatest thickness (2.56 +/- 0.47 mm), significantly (P < 0.001) greater than that of the posterior cortex (2.11 +/- 0.27 mm), medial cortex (2.20 +/- 0.39 mm) and lateral cortex (2.03 +/- 0.29 mm). The vBMD of the posterior cortex was a significant 6.5% higher than that of the anterior cortex (P < 0.001); whereas the anterior cortical thickness was a significant 21.3% greater than that of the posterior cortex (P < 0.001). There was no linear relationship found between cortical vBMD and cortical thickness measured at the four cortical regions (r = 0.086, P > 0.05). In conclusion, the regional differences, with higher vBMD found in posterior cortex, might be a result of mechanical adaptation, which caused the posterior cortex to sustain higher compressive loading than the anterior tensile cortex during the landing phase in the gait cycles of individuals. Nevertheless, regional geometric adaptation in anterior cortical thickness might be adapted to accommodate for the reduced vBMD and to reduce the bending stress in this region. PMID:15777653

Lai, Y M; Qin, L; Hung, V W Y; Chan, K M

2005-03-01

173

Thrust bearing  

NASA Technical Reports Server (NTRS)

A gas lubricated thrust bearing is described which employs relatively rigid inwardly cantilevered spokes carrying a relatively resilient annular member or annulus. This annulus acts as a beam on which are mounted bearing pads. The resilience of the beam mount causes the pads to accept the load and, with proper design, responds to a rotating thrust-transmitting collar by creating a gas film between the pads and the thrust collar. The bearing may be arranged for load equalization thereby avoiding the necessity of gimbal mounts or the like for the bearing. It may also be arranged to respond to rotation in one or both directions.

Anderson, W. J. (inventor)

1976-01-01

174

Challenging Gait Conditions Predict 1-Year Decline in Gait Speed in Older Adults With Apparently Normal Gait  

PubMed Central

Background Mobility often is tested under a low challenge condition (ie, over a straight, uncluttered path), which often fails to identify early mobility difficulty. Tests of walking during challenging conditions may uncover mobility difficulty that is not identified with usual gait testing. Objective The purpose of this study was to determine whether gait during challenging conditions predicts decline in gait speed over 1 year in older people with apparently normal gait (ie, gait speed of ?1.0 m/s). Design This was a prospective cohort study. Methods Seventy-one older adults (mean age=75.9 years) with a usual gait speed of ?1.0 m/s participated. Gait was tested at baseline under 4 challenging conditions: (1) narrow walk (15 cm wide), (2) stepping over obstacles (15.24 cm [6 in] and 30.48 cm [12 in]), (3) simple walking while talking (WWT), and (4) complex WWT. Usual gait speed was recorded over a 4-m course at baseline and 1 year later. A 1-year change in gait speed was calculated, and participants were classified as declined (decreased ?0.10 m/s, n=18), stable (changed <0.10 m/s, n=43), or improved (increased ?0.10 m/s, n=10). Analysis of variance was used to compare challenging condition cost (usual ? challenging condition gait speed difference) among the 3 groups. Results Participants who declined in the ensuing year had a greater narrow walk and obstacle walk cost than those who were stable or who improved in gait speed (narrow walk cost=0.43 versus 0.33 versus 0.22 m/s and obstacle walk cost=0.35 versus 0.26 versus 0.13 m/s). Simple and complex WWT cost did not differ among the groups. Limitations The participants who declined in gait speed over time walked the fastest, and those who improved walked the slowest at baseline; thus, the potential contribution of regression to the mean to the findings should not be overlooked. Conclusions In older adults with apparently normal gait, the assessment of gait during challenging conditions appears to uncover mobility difficulty that is not identified by usual gait testing. PMID:22003167

Perera, Subashan; VanSwearingen, Jessie M.; Hile, Elizabeth S.; Wert, David M.; Studenski, Stephanie A.

2011-01-01

175

Cryogenic Magnetic Bearing Test Facility (CMBTF)  

NASA Technical Reports Server (NTRS)

The Cryogenic Magnetic Bearing Test Facility (CMBTF) was designed and built to evaluate compact, lightweight magnetic bearings for use in the SSME's (space shuttle main engine) liquid oxygen and liquid hydrogen turbopumps. State of the art and tradeoff studies were conducted which indicated that a hybrid permanent magnet bias homopolar magnetic bearing design would be smaller, lighter, and much more efficient than conventional industrial bearings. A test bearing of this type was designed for the test rig for use at both room temperature and cryogenic temperature (-320 F). The bearing was fabricated from state-of-the-art materials and incorporated into the CMBTF. Testing at room temperature was accomplished at Avcon's facility. These preliminary tests indicated that this magnetic bearing is a feasible alternative to older bearing technologies. Analyses showed that the hybrid magnetic bearing is one-third the weight, considerably smaller, and uses less power than previous generations of magnetic bearings.

1992-01-01

176

Gait patterns in Prader-Willi and Down syndrome patients  

PubMed Central

Background Prader-Willi (PWS) and Down Syndrome (DS) are two genetic disorders characterised by some common clinical and functional features. A quantitative description and comparison of their patterns would contribute to a deeper understanding of the determinants of motor disability in these two syndromes. The aim of this study was to measure gait pattern in PWS and DS in order to provide data for developing evidence-based deficit-specific or common rehabilitation strategies. Methods 19 PWS patients (17.7-40 yr) and 21 DS patients (18-39 yr) were evaluated with an optoelectronic system and force platforms for measuring kinematic and kinetic parameters during walking. The results were compared with those obtained in a group of normal-weight controls (Control Group: CG; 33.4 + 9.6 yr). Results and Discussion The results show that PWS and DS are characterised by different gait strategies. Spatio-temporal parameters indicated a cautious, abnormal gait in both groups, but DS walked with a less stable strategy than PWS. As for kinematics, DS showed a significantly reduced hip and knee flexion, especially at initial contact and ankle range of motion than PWS. DS were characterised by lower ranges of motion (p < 0.05) in all joints than CG and PWS. As for ankle kinetics, both PWS and DS showed a significantly lower push-off during terminal stance than CG, with DS yielding the lowest values. Stiffness at hip and ankle level was increased in DS. PWS showed hip stiffness values close to normal. At ankle level, stiffness was significantly decreased in both groups. Conclusions Our data show that DS walk with a less physiological gait pattern than PWS. Based on our results, PWS and DS patients need targeted rehabilitation and exercise prescription. Common to both groups is the aim to improve hypotonia, muscle strength and motor control during gait. In DS, improving pelvis and hip range of motion should represent a major specific goal to optimize gait pattern. PMID:20565926

2010-01-01

177

49 CFR 229.69 - Side bearings.  

Code of Federal Regulations, 2010 CFR

... Suspension System § 229.69 Side bearings. (a) Friction side bearings with springs designed to carry weight may not...than 25 percent of the springs in any one nest broken. (b) Friction side bearings may not be run in contact unless designed to...

2010-10-01

178

49 CFR 229.69 - Side bearings.  

Code of Federal Regulations, 2012 CFR

... Suspension System § 229.69 Side bearings. (a) Friction side bearings with springs designed to carry weight may not...than 25 percent of the springs in any one nest broken. (b) Friction side bearings may not be run in contact unless designed to...

2012-10-01

179

Polar Bear  

USGS Publications Warehouse

Polar bears are long-lived, late-maturing carnivores that have relatively low rates of reproduction and natural mortality. Their populations are susceptible to disturbance from human activities, such as the exploration and development of mineral resources or hunting. Polar bear populations have been an important renewable resource available to coastal communities throughout the Arctic for thousands of years.

Amstrup, S.D.; DeMaster

1988-01-01

180

Periodical gait asymmetry assessment using real-time wireless gyroscopes gait monitoring system.  

PubMed

A real-time gait monitoring system that incorporates an immediate and periodical assessment of gait asymmetry is described. This system was designed for gait analysis and rehabilitation of patients with pathologic gait. It employs wireless gyroscopes to measure the angular rate of the thigh and shank in real time. Cross-correlation of the lower extremity (Cc(norm)), and normalized Symmetry Index (SI(norm)) are implemented as new approaches to periodically determine the gait asymmetry in each gait cycle. Cc(norm) evaluates the signal patterns measured by wireless gyroscopes in each gait cycle. SI(norm) determines the movement differences between the left and right limb. An experimental study was conducted to examine the viability of these methods. Artificial asymmetrical gait was simulated by placing a load on one side of the limbs. Results showed that there were significant differences between the normal gait and asymmetrical gait (p < 0.01). They also indicated that the system worked well in periodically assessing the gait asymmetry. PMID:22074136

Gouwanda, D; Senanayake, S M N A

2011-11-01

181

A gait index may underestimate changes of gait: a comparison of the Movement Deviation Profile and the Gait Deviation Index.  

PubMed

The ability of the Movement Deviation Profile (MDP) and Gait Deviation Index (GDI) to detect gait changes was compared in a child with cerebral palsy who underwent game training. Conventional gait analysis showed that sagittal plane angles became mirrored about normality after training. Despite considerable gait changes, the GDI showed minimal change, while the MDP detected a difference equal to a shift between 10-9 on the Functional Assessment Questionnaire scale. Responses of the GDI and MDP were examined during a synthetic transition of the patient's curves from before intervention to a state mirrored about normality. The GDI showed a symmetric response on the two opposite sides of normality but the neural network based MDP gave an asymmetric response reflecting faithfully the unequal biomechanical consequences of joint angle changes. In conclusion, the MDP can detect altered gait even if the changes are missed by the GDI. PMID:23521124

Barton, Gabor J; Hawken, Malcolm B; Holmes, Gill; Schwartz, Michael H

2015-01-01

182

Design and development of a simple, low cost gait training assistive device  

Microsoft Academic Search

Treadmill training with body weight support has promise in the rehabilitation of individuals with incomplete spinal cord injury. Currently, therapists manually assist the patient during gait training or mechanical orthoses drive the patient's legs. Manual training provided by physical therapists is demanding and labor intensive, while mechanical\\/robotic assist systems are expensive, immobile, and complex to setup and utilize by therapists.

R. B. Knight; J. He; M. R. Carhart; J. Koeneman

2003-01-01

183

Gait Curves for Human Recognition, Backpack Detection and Silhouette Correction in a Nighttime Environment  

E-print Network

information such as gender, height, weight, age and ethnicity to improve the recognition accuracy of biometric in mathematically quantifying an individual's gait. Nearly all methods begin with the extraction of a binary by errors due to changes in clothing or differences in camera view. However, the increased model complexity

Ross, Arun Abraham

184

A sensor-based framework for detecting human gait cycles using acceleration signals  

Microsoft Academic Search

An accelerometer-based motion sensing framework is developed for analyzing human motion (gait). In comparison to vision based motion sensing systems, this framework is extremely low in cost and weight, and is also portable to wide variety of places; even to the patient's personal room. On the other hand the device has minimum affect on the patient's normal motion. In this

Mahsa Salehi; Mohammadreza Razzazi

2009-01-01

185

A novel platform system for gait analysis  

Microsoft Academic Search

A novel platform system for gait analysis was developed, with its two main parts: force platform and pressure platform, it can offer complete components of pressures in walking, including vertical pressure, shear forces, pressure distribution and COP (centre of pressure) with reliable result. System configuration was introduced as an important part, and gait model was established. Some examples of application

Su Xu; Xu Zhou; Yi-Ning Sun

2008-01-01

186

Markerless Human Motion Capture for Gait Analysis  

Microsoft Academic Search

The aim of our study is to detect balance disorders and a tendency towards the falls in the elderly, knowing gait parameters. In this paper we present a new tool for gait analysis based on markerless human motion capture, from camera feeds. The system introduced here, recovers the 3D positions of several key points of the human body while walking.

Jamal Saboune; François Charpillet

2005-01-01

187

Gait information flow indicates complex motor dysfunction  

Microsoft Academic Search

Gait-related back movements require coordination of multiple extremities including the flexible trunk. Ageing and chronic back pain influence these adjustments. These complex coordinations can advantageously be quantified by information theoretically based communication measures such as the gait information flow (GIF). Nine back pain patients (aged 61 ± 10yr) and 12 controls (aged 38 ± 10yr) were investigated during normal walking

Dirk Hoyer; Ulf Kletzin; Daniela Adler; Steffen Adler; Winfried Meissner; Reinhard Blickhan

2005-01-01

188

Average Gait Differential Image Based Human Recognition  

PubMed Central

The difference between adjacent frames of human walking contains useful information for human gait identification. Based on the previous idea a silhouettes difference based human gait recognition method named as average gait differential image (AGDI) is proposed in this paper. The AGDI is generated by the accumulation of the silhouettes difference between adjacent frames. The advantage of this method lies in that as a feature image it can preserve both the kinetic and static information of walking. Comparing to gait energy image (GEI), AGDI is more fit to representation the variation of silhouettes during walking. Two-dimensional principal component analysis (2DPCA) is used to extract features from the AGDI. Experiments on CASIA dataset show that AGDI has better identification and verification performance than GEI. Comparing to PCA, 2DPCA is a more efficient and less memory storage consumption feature extraction method in gait based recognition. PMID:24895648

Chen, Jinyan; Liu, Jiansheng

2014-01-01

189

Pathology Case Study: Gait Disorders  

NSDL National Science Digital Library

This is a case study presented by the University of Pittsburgh Department of Pathology, which describes a 62-year-old woman with a 20-year history of gait disorders and dizziness. Visitors are given patient history, laboratory findings, along with microscopic descriptions, including images, and are given the opportunity to diagnose the patient. A "Final Diagnosis" section provides a discussion of the findings as well as references. This is an excellent resource for students in the health sciences to familiarize themselves with using patient history and laboratory results to diagnose disease. It is also a helpful site for educators to use to introduce or test student learning in neuropathology.

2009-04-21

190

Development of the Gait Assistant Mobile Robot using Ergonomic Design  

Microsoft Academic Search

In this study, the concept of autonomous mobility is applied to a gait support mobile robot. The aim of the development of the service robot is to assist the elderly with gait assistant. This study proposes an ergonomic service robot design parameter. The gait assistant path pattern is derived from analysis of the elderly gait. A lever is installed in

Tong-jin Park; Chang-soo Han; Jung-soo Han; Ho-Gil Lee

2004-01-01

191

Effect of Treadmill Training on Specific Gait Parameters in Older Adults with Frailty: Case Series  

PubMed Central

Background and Purpose Treadmill walking training (TWT) as an intervention to improve the gait of frail older adults has not been well studied. In this pilot study, we describe the feasibility, tolerance, and effect of TWT on specific gait parameters during overground walking in four frail older adults as a prelude to developing larger scale exercise intervention trials in this high-risk population. Case Description Four community-residing frail older individuals (age>70) with Mini-Mental Status Examination score of 26 or higher and no activity limitations. Frailty was defined as presence of at least three out of the following five attributes: slow gait (<1 m/sec), unintentional weight loss (>10 lbs in prior year), self-report of poor grip strength, exhaustion, and low level of physical activity. Intervention TWT consisted of 24 sessions (3 times/week for 8 weeks). Five quantitative gait parameters [velocity, stride length, swing time, percentage of double support phase, coefficient of variation (COV) of stride length] during overground walking were measured at baseline, weekly during training, and immediately post-TWT. Outcome All participants tolerated TWT without significant complications. Following TWT, gait velocity increased in all participants by 6.4 to 26.8 cm/sec, which was larger than the reported value for meaningful change in gait velocity (4 cm/sec). Stride length and double support phase also showed improvement in all participants (mean percentage increase of 10.8 % for stride length, and 17.1% reduction for double support phase post training compared to baseline). Swing time improved in three participants (mean reduction of 4.5 %). The COV of stride length did not show consistent improvement. Discussion This case series shows that TWT is feasible and well tolerated by frail older adults, and may improve most gait parameters in this high-risk population. PMID:22124418

Holtzer, Roee; Mahoney, Jeannette; Wang, Cuiling; Verghese, Joe

2011-01-01

192

Foil bearings  

NASA Astrophysics Data System (ADS)

The rolling element bearings (REB's) which support many turbomachinery rotors offer high load capacity, low power requirements, and durability. Two disadvantages of REB's are: (1) rolling or sliding contact within the bearing has life-limiting consequences; and (2) REB's provide essentially no damping. The REB's in the Space Shuttle Main Engine (SSME) turbopumps must sustain high static and dynamic loads, at high speeds, with a cryogenic fluid as lubricant and coolant. The pump end ball bearings limit the life of the SSME high pressure oxygen turbopump (HPOTP). Compliant foil bearing (CFB) manufacturers have proposed replacing turbopump REB's with CFB's CFB's work well in aircraft air cycle machines, auxiliary power units, and refrigeration compressors. In a CFB, the rotor only contracts the foil support structure during start up and shut down. CFB damping is higher than REB damping. However, the load capacity of the CFB is low, compared to a REB. Furthermore, little stiffness and damping data exists for the CFB. A rotordynamic analysis for turbomachinery critical speeds and stability requires the input of bearing stiffness and damping coefficients. The two basic types of CFB are the tension-dominated bearing and the bending-dominated bearing. Many investigators have analyzed and measured characteristics of tension-dominated foil bearings, which are applied principally in magnetic tape recording. The bending-dominated CFB is used more in rotating machinery. This report describes the first phase of a structural analysis of a bending-dominated, multileaf CFB. A brief discussion of CFB literature is followed by a description and results of the present analysis.

Elrod, David A.

1993-11-01

193

Foil bearings  

NASA Technical Reports Server (NTRS)

The rolling element bearings (REB's) which support many turbomachinery rotors offer high load capacity, low power requirements, and durability. Two disadvantages of REB's are: (1) rolling or sliding contact within the bearing has life-limiting consequences; and (2) REB's provide essentially no damping. The REB's in the Space Shuttle Main Engine (SSME) turbopumps must sustain high static and dynamic loads, at high speeds, with a cryogenic fluid as lubricant and coolant. The pump end ball bearings limit the life of the SSME high pressure oxygen turbopump (HPOTP). Compliant foil bearing (CFB) manufacturers have proposed replacing turbopump REB's with CFB's CFB's work well in aircraft air cycle machines, auxiliary power units, and refrigeration compressors. In a CFB, the rotor only contracts the foil support structure during start up and shut down. CFB damping is higher than REB damping. However, the load capacity of the CFB is low, compared to a REB. Furthermore, little stiffness and damping data exists for the CFB. A rotordynamic analysis for turbomachinery critical speeds and stability requires the input of bearing stiffness and damping coefficients. The two basic types of CFB are the tension-dominated bearing and the bending-dominated bearing. Many investigators have analyzed and measured characteristics of tension-dominated foil bearings, which are applied principally in magnetic tape recording. The bending-dominated CFB is used more in rotating machinery. This report describes the first phase of a structural analysis of a bending-dominated, multileaf CFB. A brief discussion of CFB literature is followed by a description and results of the present analysis.

Elrod, David A.

1993-01-01

194

Gait instability and fractal dynamics of older adults with a “cautious” gait: why do certain older adults walk fearfully?  

Microsoft Academic Search

Many older adults walk with a cautious and impaired gait of unknown origin, however, the relationship between fear of falling and the observed gait changes is not well understood. To better understand the “cautious” gait of the elderly, we tested the hypothesis that temporal gait variability, putatively a marker of intrinsic walking unsteadiness, is increased among older adults with a

T. Herman; N. Giladi; T. Gurevich; J. M. Hausdorff

2005-01-01

195

Body size and walking cadence affect lower extremity joint power in children's gait  

Microsoft Academic Search

Obese children move less and with greater difficulty than normal-weight counterparts but expend comparable energy. Increased metabolic costs have been attributed to poor biomechanics but few studies have investigated the influence of obesity on mechanical demands of gait. This study sought to assess three-dimensional lower extremity joint powers in two walking cadences in 28 obese and normal-weight children. 3D-motion analysis

Sarah P. Shultz; Andrew P. Hills; Michael R. Sitler; Howard J. Hillstrom

2010-01-01

196

Investigation of first ray mobility during gait by kinematic fluoroscopic imaging-a novel method  

PubMed Central

Background It is often suggested that sagittal instability at the first tarso-metatarsal joint level is a primary factor for hallux valgus and that sagittal instability increases with the progression of the deformity. The assessment of the degree of vertical instability is usually made by clinical evaluation while any measurements mostly refer to a static assessment of medial ray mobility (i.e. the plantar/dorsal flexion in the sagittal plane). Testing methods currently available cannot attribute the degree of mobility to the corresponding anatomical joints making up the medial column of the foot. The aim of this study was to develop a technique which allows for a quantification of the in-vivo sagittal mobility of the joints of the medial foot column during the roll-over process under full weight bearing. Methods Mobility of first ray bones was investigated by dynamic distortion-free fluoroscopy (25 frames/s) of 14 healthy volunteers and 8 patients with manifested clinical instability of the first ray. A CAD-based evaluation method allowed the determination of mobility and relative displacements and rotations of the first ray bones within the sagittal plane during the stance phase of gait. Results Total flexion of the first ray was found to be 13.63 (SD 6.14) mm with the healthy volunteers and 13.06 (SD 8.01) mm with the patients (resolution: 0.245 mm/pixel). The dorsiflexion angle was 5.27 (SD 2.34) degrees in the healthy volunteers and increased to 5.56 (SD 3.37) degrees in the patients. Maximum rotations were found at the naviculo-cuneiform joints and least at the first tarso-metatarsal joint level in both groups. Conclusions Dynamic fluoroscopic assessment has been shown to be a valuable tool for characterisation of the kinematics of the joints of the medial foot column during gait. A significant difference in first ray flexion and angular rotation between the patients and healthy volunteers however could not be found. PMID:22316084

2012-01-01

197

Motion cue analysis for parkinsonian gait recognition.  

PubMed

This paper presents a computer-vision based marker-free method for gait-impairment detection in Patients with Parkinson's disease (PWP). The system is based upon the idea that a normal human body attains equilibrium during the gait by aligning the body posture with Axis-of-Gravity (AOG) using feet as the base of support. In contrast, PWP appear to be falling forward as they are less-able to align their body with AOG due to rigid muscular tone. A normal gait exhibits periodic stride-cycles with stride-angle around 45o between the legs, whereas PWP walk with shortened stride-angle with high variability between the stride-cycles. In order to analyze Parkinsonian-gait (PG), subjects were videotaped with several gait-cycles. The subject's body was segmented using a color-segmentation method to form a silhouette. The silhouette was skeletonized for motion cues extraction. The motion cues analyzed were stride-cycles (based on the cyclic leg motion of skeleton) and posture lean (based on the angle between leaned torso of skeleton and AOG). Cosine similarity between an imaginary perfect gait pattern and the subject gait patterns produced 100% recognition rate of PG for 4 normal-controls and 3 PWP. Results suggested that the method is a promising tool to be used for PG assessment in home-environment. PMID:23407764

Khan, Taha; Westin, Jerker; Dougherty, Mark

2013-01-01

198

Motion Cue Analysis for Parkinsonian Gait Recognition  

PubMed Central

This paper presents a computer-vision based marker-free method for gait-impairment detection in Patients with Parkinson’s disease (PWP). The system is based upon the idea that a normal human body attains equilibrium during the gait by aligning the body posture with Axis-of-Gravity (AOG) using feet as the base of support. In contrast, PWP appear to be falling forward as they are less-able to align their body with AOG due to rigid muscular tone. A normal gait exhibits periodic stride-cycles with stride-angle around 45o between the legs, whereas PWP walk with shortened stride-angle with high variability between the stride-cycles. In order to analyze Parkinsonian-gait (PG), subjects were videotaped with several gait-cycles. The subject’s body was segmented using a color-segmentation method to form a silhouette. The silhouette was skeletonized for motion cues extraction. The motion cues analyzed were stride-cycles (based on the cyclic leg motion of skeleton) and posture lean (based on the angle between leaned torso of skeleton and AOG). Cosine similarity between an imaginary perfect gait pattern and the subject gait patterns produced 100% recognition rate of PG for 4 normal-controls and 3 PWP. Results suggested that the method is a promising tool to be used for PG assessment in home-environment. PMID:23407764

Khan, Taha; Westin, Jerker; Dougherty, Mark

2013-01-01

199

Gait transitions in simulated reduced gravity.  

PubMed

Gravity has a strong effect on gait and the speed of gait transitions. A gait has been defined as a pattern of locomotion that changes discontinuously at the transition to another gait. On Earth, during gradual speed changes, humans exhibit a sudden discontinuous switch from walking to running at a specific speed. To study the effects of altered gravity on both the stance and swing legs, we developed a novel unloading exoskeleton that allows a person to step in simulated reduced gravity by tilting the body relative to the vertical. Using different simulation techniques, we confirmed that at lower gravity levels the transition speed is slower (in accordance with the previously reported Froude number ?0.5). Surprisingly, however, we found that at lower levels of simulated gravity the transition between walking and running was generally gradual, without any noticeable abrupt change in gait parameters. This was associated with a significant prolongation of the swing phase, whose duration became virtually equal to that of stance in the vicinity of the walk-run transition speed, and with a gradual shift from inverted-pendulum gait (walking) to bouncing gait (running). PMID:21212248

Ivanenko, Yuri P; Labini, Francesca Sylos; Cappellini, Germana; Macellari, Velio; McIntyre, Joseph; Lacquaniti, Francesco

2011-03-01

200

Adaptive method for real-time gait phase detection based on ground contact forces.  

PubMed

A novel method is presented to detect real-time gait phases based on ground contact forces (GCFs) measured by force sensitive resistors (FSRs). The traditional threshold method (TM) sets a threshold to divide the GCFs into on-ground and off-ground statuses. However, TM is neither an adaptive nor real-time method. The threshold setting is based on body weight or the maximum and minimum GCFs in the gait cycles, resulting in different thresholds needed for different walking conditions. Additionally, the maximum and minimum GCFs are only obtainable after data processing. Therefore, this paper proposes a proportion method (PM) that calculates the sums and proportions of GCFs wherein the GCFs are obtained from FSRs. A gait analysis is then implemented by the proposed gait phase detection algorithm (GPDA). Finally, the PM reliability is determined by comparing the detection results between PM and TM. Experimental results demonstrate that the proposed PM is highly reliable in all walking conditions. In addition, PM could be utilized to analyze gait phases in real time. Finally, PM exhibits strong adaptability to different walking conditions. PMID:25468687

Yu, Lie; Zheng, Jianbin; Wang, Yang; Song, Zhengge; Zhan, Enqi

2015-01-01

201

Controlling patient participation during robot-assisted gait training  

PubMed Central

Background The overall goal of this paper was to investigate approaches to controlling active participation in stroke patients during robot-assisted gait therapy. Although active physical participation during gait rehabilitation after stroke was shown to improve therapy outcome, some patients can behave passively during rehabilitation, not maximally benefiting from the gait training. Up to now, there has not been an effective method for forcing patient activity to the desired level that would most benefit stroke patients with a broad variety of cognitive and biomechanical impairments. Methods Patient activity was quantified in two ways: by heart rate (HR), a physiological parameter that reflected physical effort during body weight supported treadmill training, and by a weighted sum of the interaction torques (WIT) between robot and patient, recorded from hip and knee joints of both legs. We recorded data in three experiments, each with five stroke patients, and controlled HR and WIT to a desired temporal profile. Depending on the patient's cognitive capabilities, two different approaches were taken: either by allowing voluntary patient effort via visual instructions or by forcing the patient to vary physical effort by adapting the treadmill speed. Results We successfully controlled patient activity quantified by WIT and by HR to a desired level. The setup was thereby individually adaptable to the specific cognitive and biomechanical needs of each patient. Conclusion Based on the three successful approaches to controlling patient participation, we propose a metric which enables clinicians to select the best strategy for each patient, according to the patient's physical and cognitive capabilities. Our framework will enable therapists to challenge the patient to more activity by automatically controlling the patient effort to a desired level. We expect that the increase in activity will lead to improved rehabilitation outcome. PMID:21429200

2011-01-01

202

Comparison of sensor systems for gait phase detection in hemiplegic gait  

Microsoft Academic Search

\\u000a Gait phase detection is important for evaluating the recovering of gait ability in patients with paralysis as well as for\\u000a determination of stimulation in FES walking. Forceplate in three dimensional system can give the most objective and accurate\\u000a information about gait phase detection, however it is very expensive and limited in restricted area of laboratory. In this\\u000a study, three different

S. W. Park; R. H. Sohn; S. H. Hwang; Y. H. Kim

203

Lubrication for high load duplex bearings  

SciTech Connect

Three ES and H-compatible lubricants (Environment, Safety and Health) for high load duplex bearing applications were evaluated and compared against trichlorotrifluoroethane (Freon) deposition of low molecular weight polytetrafluoroethylene (PTFE) bearing lubricant extracted from Vydax{trademark}. Vydax is a product manufactured by DuPont consisting of various molecular weights of PTFE suspended in trichlorotrifluoroethane (Freon) which is an ozone-depleting solvent. Bearings with Supercritical CO{sub 2} deposition of PTFE extracted from Vydax AR/IPA, bearings with titanium carbide coated balls, and bearings with diamond-like carbon races and retainers were evaluated. Bearings with Supercritical CO{sub 2} deposition of PTFE from Vydax AR/IPA performed as well as bearings with Freon deposition of PTFE from Freon-based Vydax.

Steinhoff, R.G.

1997-08-01

204

Cave Bear  

NSDL National Science Digital Library

Decoding an ancient cave bear. A two-ton, thirteen-foot cave bear, extinct for ten thousand years, has just experienced a rebirth of sorts. From a tooth and a bone, scientists have recovered its entire genetic code.Eddy Rubin, director of the Department of Energy's Joint Genome Institute, says finding genuine cave bear DNA was like looking for a needle in a haystack. The haystack were all the other organisms that were living in the bones and in the tooth of this ancient creature. And the needle was the little bit of the ancient creature's genome DNA, or genes.They used state-of-the-art computer technology to separate the bear genes from the clutter. Jurassic Park fans should note that they can't clone a new cave bear, nor can they recover DNA from creatures as old as the dinosaurs. But they do hope to reconstruct the genetic code of Neanderthals, our closest non-human relatives, to better understand how our own species evolved. This resource contains detailed text description of the research as well as likes for further inquiry.

American Association for the Advancement of Science (; )

2005-08-15

205

Gait recognition based on Gabor wavelets and modified gait energy image for human identification  

NASA Astrophysics Data System (ADS)

This paper proposes a method for recognizing human identity using gait features based on Gabor wavelets and modified gait energy images (GEIs). Identity recognition by gait generally involves gait representation, extraction, and classification. In this work, a modified GEI convolved with an ensemble of Gabor wavelets is proposed as a gait feature. Principal component analysis is then used to project the Gabor-wavelet-based gait features into a lower-dimension feature space for subsequent classification. Finally, support vector machine classifiers based on a radial basis function kernel are trained and utilized to recognize human identity. The major contributions of this paper are as follows: (1) the consideration of the shadow effect to yield a more complete segmentation of gait silhouettes; (2) the utilization of motion estimation to track people when walkers overlap; and (3) the derivation of modified GEIs to extract more useful gait information. Extensive performance evaluation shows a great improvement of recognition accuracy due to the use of shadow removal, motion estimation, and gait representation using the modified GEIs and Gabor wavelets.

Huang, Deng-Yuan; Lin, Ta-Wei; Hu, Wu-Chih; Cheng, Chih-Hsiang

2013-10-01

206

Multiple views gait recognition using view transformation model based on optimized gait energy image  

E-print Network

Gait is one of well recognized biometrics that has been widely used for human identification. However, the current gait recognition might have difficulties due to viewing angle being changed. This is because the viewing angle under which the gait signature database was generated may not be the same as the viewing angle when the probe data are obtained. This paper proposes a new multi-view gait recognition approach which tackles the problems mentioned above. Being different from other approaches of same category, this new method creates a so called View Transformation Model (VTM) based on spatial-domain Gait Energy Image (GEI) by adopting Singular Value Decomposition (SVD) technique. To further improve the performance of the proposed VTM, Linear Discriminant Analysis (LDA) is used to optimize the obtained GEI feature vectors. When implementing SVD there are a few practical problems such as large matrix size and over-fitting. In this paper, reduced SVD is introduced to alleviate the effects caused by these problems. Using the generated VTM, the viewing angles of gallery gait data and probe gait data can be transformed into the same direction. Thus, gait signatures can be measured without difficulties. The extensive experiments show that the proposed algorithm can significantly improve the multiple view gait recognition performance when being compared to the similar methods in literature. 1.

Worapan Kusakunniran; Qiang Wu; Hongdong Li; Jian Zhang

207

Design of a robot for gait rehabilitation  

E-print Network

The ability to walk is important for independent living and when this capacity is affected by injury, gait therapy is the traditional approach to re-train the nervous system, to re-build muscle strength, to improve balance, ...

Bosecker, Caitlyn Joyce

2009-01-01

208

Quantitative gait disturbances in older adults with cognitive impairments.  

PubMed

Gait is a complex motor task, initiated and governed by different areas of the brain. Studies have shown a clear association between gait and cognition. Impairments in both gait and cognition are prevalent in older adults. Older adults with gait impairment have an increased risk of developing cognitive impairments. Those with cognitive impairment often have gait impairments and more falls than cognitively healthy older adults. Recent studies have shown that quantitative gait analysis, particularly performed during dual task conditions, can detect gait deficits that cannot yet be seen by the naked eye, even to a trained specialist. Some studies have shown that such gait disturbances were measurable years before mild cognitive impairment or dementia or walking difficulties were clinically manifest. Quantitative gait analysis can provide early detection of gait and cognitive impairments as well as fall risk. Future quantitative gait studies may help distinguish dementia subtypes in early stages of the diseases. Early detection of gait and cognitive impairments would provide a better understanding of disease pathophysiology and progression. Early detection also allows the timely implementation of interventions with the ultimate goal of improving or maintaining mobility and functional independence for as long as possible. Quantitative gait analysis should be viewed as a clinical tool to aid diagnoses and treatment planning. This review examines the current literature on quantitatively measured gait impairment in older adults with mild cognitive impairment or a dementia subtype. PMID:24050167

Bridenbaugh, Stephanie A; Kressig, Reto W

2014-01-01

209

DYNAMICS OF GAIT IN ACTIVE ELDERLY MEN  

Microsoft Academic Search

The purpose of this study was to identify if, on very active elderly male, the undesirables effects of age in gait dynamic variables where minimized. The gait cycle of 3 healthy and active elderly males (ages: 69.30±1.41 years) and 5 health and active young males (ages: 21.80±0.45 years) was compared in order to verify if the differences (between young and

Filipa João; Vera Moniz Pereira; António Veloso

2007-01-01

210

COHERENCE OF GAIT AND MENTAL WORKLOAD  

Microsoft Academic Search

\\u000a We propose a spectral analytical approach to evaluate the coordination of gait and mental task. Our hypothesis is that when\\u000a the mental workloads and the gait control are coherent, the capability to recover from or prepare for a perturbation is enhanced.\\u000a Such analysis is critical for conducting safe foot patrols or walking inspection jobs, for examples, police, foot soldier,\\u000a immigration

S. M. Hsiang; T. Karakostas; C.-C. Chang; S. Ekwaro-Osire

211

Bear Bones  

NSDL National Science Digital Library

An estimated ten million Americans have osteoporosis, an age-related disease in which the bones gradually become brittle and weak. Now, scientists are looking to animals for clues on how to combat this condition. This resource describes the study of sustaining bone strength of hibernating bears.

Science Update;

2004-03-08

212

Automated event detection algorithms in pathological gait.  

PubMed

Accurate automated event detection is important in increasing the efficiency and utility of instrumented gait analysis. Published automated event detection algorithms, however, have had limited testing on pathological populations, particularly those where force measurements are not available or reliable. In this study we first postulated robust definitions of gait events that were subsequently used to compare kinematic based event detection algorithms across difficult pathologies. We hypothesized that algorithm accuracy would vary by gait pattern, and that accurate event detection could be accomplished by first visually classifying the gait pattern, and subsequently choosing the most appropriate algorithm. Nine published kinematic event detection algorithms were applied to an existing instrumented pediatric gait database (primarily cerebral palsy pathologies), that were categorized into 4 visually distinct gait patterns. More than 750 total events were manually rated and these events were used as a gold standard for comparison to each algorithm. Results suggested that for foot strike events, algorithm choice was dependent on whether the foot's motion in terminal swing was more horizontal or vertical. For horizontal foot motion in swing, algorithms that used horizontal position, resultant sagittal plane velocity, or horizontal acceleration signals were most robust; while for vertical foot motion, resultant sagittal velocity or vertical acceleration excelled. For toe off events, horizontal position or resultant sagittal plane velocity performed the best across all groups. We also tuned the resultant sagittal plane velocity signal to walking speed to create an algorithm that can be used for all groups and in real time. PMID:24041468

Bruening, Dustin A; Ridge, Sarah Trager

2014-01-01

213

Attempt toward a development of aquatic exercise device for gait disorders.  

PubMed

Abstract Purpose: To develop an aquatic exercise device to facilitate locomotive motor output and achieve repetitive physiological gait patterns to improve movement dysfunctions. Methods: A custom designed leg movement apparatus (LMA) consisted of closed 4-linkage mechanisms and one-length changeable link using a spring. Three-dimensional motions and electromyographic (EMG) activities were recorded in eight healthy subjects to evaluate the reproducibility of the physiological gait patterns using the LMA with or without a spring apparatus in water. Results: Using the LMA with a spring apparatus compared to walking in water, the foot trajectories and the time course of the elevation angles in each lower limb joint kinematics were preserved. The time-series of the EMG showed reciprocal modulation between agonist and antagonist muscle groups in the hip and ankle joints. However, the amplitudes of the tibialis anterior muscle in the first half and rectus femoris in the last half of the movement cycle were reduced using the LMA with a spring apparatus. Conclusion: We developed a novel aquatic exercise device to reproduce physiological gait patterns. The LMA with a spring apparatus would be particularly valuable in therapy for movement dysfunctions to facilitate locomotive motor outputs. Implications for Rehabilitation The leg movement apparatus with spring for underwater use (LMA) would be effective gait training to induce the locomotor-like EMG activities. Hydrotherapy with the LMA has advantages over the partial body weight support treadmill training on land with a robotic device; (1) the LMA is electrically and mechanically safe, and (2) the LMA would require self-effort to generate the gait pattern for movement disorders, or also enable passive gait training by the physiotherapists. PMID:24856666

Miyoshi, Tasuku; Komatsu, Fumie; Takagi, Motoki; Kawashima, Noritaka

2014-05-23

214

Tooling Converts Stock Bearings To Custom Bearings  

NASA Technical Reports Server (NTRS)

Technique for reworking stock bearings saves time and produces helicopter-rotor bearings ground more precisely. Split tapered ring at one end of threaded bolt expands to hold inside of inner race bearing assembly; nut, at other end of bolt, adjusts amount of spring tension. Piece of hardware grasps bearing firmly without interfering with grinding operation. Operation produces bearing of higher quality than commercially available bearings.

Fleenor, E. N., Jr.

1983-01-01

215

Gait Initiation in Children with Rett Syndrome  

PubMed Central

Rett syndrome is an X-linked neurodevelopmental condition mainly characterized by loss of spoken language and a regression of purposeful hand use, with the development of distinctive hand stereotypies, and gait abnormalities. Gait initiation is the transition from quiet stance to steady-state condition of walking. The associated motor program seems to be centrally mediated and includes preparatory adjustments prior to any apparent voluntary movement of the lower limbs. Anticipatory postural adjustments contribute to postural stability and to create the propulsive forces necessary to reach steady-state gait at a predefined velocity and may be indicative of the effectiveness of the feedforward control of gait. In this study, we examined anticipatory postural adjustments associated with gait initiation in eleven girls with Rett syndrome and ten healthy subjects. Muscle activity (tibialis anterior and soleus muscles), ground reaction forces and body kinematic were recorded. Children with Rett syndrome showed a distinctive impairment in temporal organization of all phases of the anticipatory postural adjustments. The lack of appropriate temporal scaling resulted in a diminished impulse to move forward, documented by an impairment in several parameters describing the efficiency of gait start: length and velocity of the first step, magnitude and orientation of centre of pressure-centre of mass vector at the instant of (swing-)toe off. These findings were related to an abnormal muscular activation pattern mainly characterized by a disruption of the synergistic activity of antagonistic pairs of postural muscles. This study showed that girls with Rett syndrome lack accurate tuning of feedforward control of gait. PMID:24743294

Isaias, Ioannis Ugo; Dipaola, Mariangela; Michi, Marlies; Marzegan, Alberto; Volkmann, Jens; Rodocanachi Roidi, Marina L.; Frigo, Carlo Albino; Cavallari, Paolo

2014-01-01

216

The role of excess mass in the adaptation of children's gait.  

PubMed

The aim of this study was to determine differences in lower extremity joint powers at weight acceptance and propulsion in obese and non-obese children during two loading conditions. Gait analyses were conducted on 20 non-obese and 20 obese children (8-12years). The first testing session was completed in a normal (unloaded) condition; an additional 10% body mass (acute loading) was added during the second session. Peak lower extremity joint power (W) phases were identified at weight acceptance and propulsion. Obese children demonstrated greater joint powers than non-obese children, at both weight acceptance and propulsion. Likewise, all children produced larger joint powers during acute loading conditions than unloaded. When body mass is a covariate, significant main effects for loading conditions remained for the hip and knee during weight acceptance and the hip and ankle at propulsion; no group differences remained significant. Obese children produced greater power generation at the hip and ankle during unloaded conditions than non-obese children during acute conditions. Only the ankle had greater power generation after accounting for body mass. The findings suggest that obese children must increase muscular contraction force to maintain normal gait function. While increased joint powers necessary for normal gait could result in incidental muscle strengthening of obese children, this persistent increase in muscular force demand could result in musculoskeletal injury. PMID:24908185

Shultz, Sarah P; D'Hondt, Eva; Lenoir, Matthieu; Fink, Philip W; Hills, Andrew P

2014-08-01

217

Relationships of Stroke Patients’ Gait Parameters with Fear of Falling  

PubMed Central

[Purpose] The purpose of this study was to assess the correlation of gait parameters with fear of falling in stroke survivors. [Subjects] In total, 12 patients with stroke participated. [Methods] The subjects performed on a Biodex Gait Trainer 2 for 5?min to evaluate characteristic gait parameters. The kinematic gait parameters measured were gait speed, step cycle, step length, and time on each foot (step symmetry). All the subjects also completed a fall anxiety survey. [Results] Correlations between gait parameters and fear of falling scores were calculated. There was a moderate degree of correlation between fear of falling scores and the step cycle item of gait parameters. [Conclusions] According to our results, the step cycle gait parameter may be related to increased fall anxiety. PMID:25540488

Park, Jin; Yoo, Ingyu

2014-01-01

218

Questions & Answers - NIH Glucosamine/Chondroitin Arthritis Intervention Trial (GAIT)  

MedlinePLUS

... than two 500 mg tablets per day. What did GAIT cost? The primary GAIT study cost just ... VA) Cooperative Studies Program Clinical Research Pharmacy. Where did the other study products come from? Acetaminophen was ...

219

Gait evaluation of biofeedback balance training for chronic stroke patients  

Microsoft Academic Search

Uneven weight bearing distribution, which leads to asymmetric characteristics of the locomotor pattern, is commonly observed among patients with hemiparesis during quasistatic stance. The purpose of this research was to investigate the effects of using a visual and auditory biofeedback system in a balance retraining program for patients in the chronic post?stroke period. Sixteen chronic patients with hemiparesis who suffered

2003-01-01

220

Gait synchronization in Caenorhabditis elegans  

PubMed Central

Collective motion is observed in swarms of swimmers of various sizes, ranging from self-propelled nanoparticles to fish. The mechanisms that govern interactions among individuals are debated, and vary from one species to another. Although the interactions among relatively large animals, such as fish, are controlled by their nervous systems, the interactions among microorganisms, which lack nervous systems, are controlled through physical and chemical pathways. Little is known, however, regarding the mechanism of collective movements in microscopic organisms with nervous systems. To attempt to remedy this, we studied collective swimming behavior in the nematode Caenorhabditis elegans, a microorganism with a compact nervous system. We evaluated the contributions of hydrodynamic forces, contact forces, and mechanosensory input to the interactions among individuals. We devised an experiment to examine pair interactions as a function of the distance between the animals and observed that gait synchronization occurred only when the animals were in close proximity, independent of genes required for mechanosensation. Our measurements and simulations indicate that steric hindrance is the dominant factor responsible for motion synchronization in C. elegans, and that hydrodynamic interactions and genotype do not play a significant role. We infer that a similar mechanism may apply to other microscopic swimming organisms and self-propelled particles. PMID:24778261

Yuan, Jinzhou; Raizen, David M.; Bau, Haim H.

2014-01-01

221

Feature extraction via KPCA for classification of gait patterns  

Microsoft Academic Search

Automated recognition of gait pattern change is important in medical diagnostics as well as in the early identification of at-risk gait in the elderly. We evaluated the use of Kernel-based Principal Component Analysis (KPCA) to extract more gait features (i.e., to obtain more significant amounts of information about human movement) and thus to improve the classification of gait patterns. 3D

Jianning Wu; Jue Wang; Li Liu

2007-01-01

222

MFC histogram and Poincare plot images for automated gait detection  

Microsoft Academic Search

In this paper, we apply support vector machines (SVMs) for the automatic recognition of young-old gait from their respective gait-patterns. Minimum foot clearance (MFC) data of 30 young and 28 elderly participants were analysed using a PEAK-2D motion analysis system. Gait features extracted from individual MFC histogram-plot and Poincare-plots were used to develop gait classification models using SVMs. Test results

R. Begg; M. Palaniswami; B. Owen; S. Taylor; L. Dell'Oro

2004-01-01

223

Towards Ubiquitous Acquisition and Processing of Gait Parameters  

Microsoft Academic Search

\\u000a Gait analysis is the process of measuring and evaluating gait and walking spatio-temporal patterns, namely of human locomotion.\\u000a This process is usually performed on specialized equipment that is capable of acquiring extensive data and providing a gait\\u000a analysis assessment based on reference values. Based on gait assessments, therapists and physicians can prescribe medications\\u000a and provide physical therapy rehabilitation to patients

Irvin Hussein López-Nava; Angélica Muñoz-Meléndez

2010-01-01

224

Predisability And Gait Patterns In Older Adults  

PubMed Central

Presence of performance inconsistency during repeated assessments of gait may reflect underlying subclinical disease, and help shed light on the earliest stages of disablement. We studied inter-session fluctuations on three selected gait measures (velocity, stride length, and stride length variability) during normal pace walking as well as during a cognitively demanding ‘walking while talking’ condition using a repeated measurement burst design (six sessions within a 2-week period) in 71 nondisabled and nondemented community residing older adults, 40 with predisability (does activities of daily living unassisted but with difficulty). Subjects with predisability had slower gait velocity and shorter stride length on both the normal and walking while talking conditions at baseline compared to nondisabled subjects. However, there was no significant pattern of fluctuations across the six sessions on the three selected gait variables comparing the two groups during normal walking as well as on the walking while talking conditions. Our findings support consistency of gait measurements during the earliest stages of disability. PMID:21050762

Verghese, Joe; Xue, Xiaonan

2010-01-01

225

The asymmetric gait toenail unit sign.  

PubMed

The aim of this investigation was to resolve a diagnostic problem and report toenail unit changes attributable to shoe friction that resemble onychomycosis, but that are fungus-negative, and identify common skeletal causes in patients with an asymmetric walking gait. X-ray and clinical feet inspections were performed to evaluate skeletal components that change normal foot biodynamics. Forty-nine patients, all dermatophyte-negative, were reviewed. All patients were those seen in our private practice who demonstrated skeletal and toenail unit abnormalities such as onycholysis, nail bed keratosis resembling distal subungual onychomycosis, nail plate surface abnormalities, distal toe skin keratosis, a diagnostic nail plate shape, as well as several skeletal abnormalities. The clinical abnormalities of the asymmetric gait syndrome include onycholysis, nail bed keratosis, nail plate surface abnormalities, and a diagnostic nail plate shape. By the patient's history, the skeletal findings that were present worsened with age and, in many patients, they were familial. Onychomycosis does not lead to an asymmetric gait nail problem, asymmetric gait toenail does not favor dermatophyte infection, and not all nail dystrophies are the result of an asymmetric walking gait. PMID:23008938

Zaias, Nardo; Rebell, Gerbert; Casal, German; Appel, Jason

2012-01-01

226

Human odometer is gait-symmetry specific.  

PubMed

In 1709, Berkeley hypothesized of the human that distance is measurable by 'the motion of his body, which is perceivable by touch'. To be sufficiently general and reliable, Berkeley's hypothesis must imply that distance measured by legged locomotion approximates actual distance, with the measure invariant to gait, speed and number of steps. We studied blindfolded human participants in a task in which they travelled by legged locomotion from a fixed starting point A to a variable terminus B, and then reproduced, by legged locomotion from B, the A-B distance. The outbound ('measure') and return ('report') gait could be the same or different, with similar or dissimilar step sizes and step frequencies. In five experiments we manipulated bipedal gait according to the primary versus secondary distinction revealed in symmetry group analyses of locomotion patterns. Berkeley's hypothesis held only when the measure and report gaits were of the same symmetry class, indicating that idiothetic distance measurement is gait-symmetry specific. Results suggest that human odometry (and perhaps animal odometry more generally) entails variables that encompass the limbs in coordination, such as global phase, and not variables at the level of the single limb, such as step length and step number, as traditionally assumed. PMID:19740881

Turvey, Michael T; Romaniak-Gross, Carissa; Isenhower, Robert W; Arzamarski, Ryan; Harrison, Steven; Carello, Claudia

2009-12-22

227

Development and Decline of Upright Gait Stability  

PubMed Central

Upright gait is a peculiar characteristic of humans that requires the ability to manage upper body dynamic balance while walking, despite the perturbations that are generated by movements of the lower limbs. Most of the studies on upright gait stability have compared young adults and the elderly to determine the effects of aging. In other studies, the comparison was between healthy subjects and patients to examine specific pathologies. Fewer researches have also investigated the development of upright gait stability in children. This review discusses these studies in order to provide an overview of this relevant aspect of human locomotion. A clear trend from development to decline of upright gait stability has been depicted across the entire lifespan, from toddlers at first steps to elderly. In old individuals, even if healthy, the deterioration of skeletal muscle, combined with sensorial and cognitive performance, reduces the ability to maintain an upright trunk during walking, increasing the instability and the risk of falls. Further, the pathological causes of altered development or of a sudden loss of gait stability, as well as the environmental influence are investigated. The last part of this review is focused on the control of upper body accelerations during walking, a particularly interesting topic for the recent development of low-cost wearable accelerometers. PMID:24550829

Iosa, Marco; Fusco, Augusto; Morone, Giovanni; Paolucci, Stefano

2014-01-01

228

Gait stability in children with cerebral palsy  

PubMed Central

Children with unilateral Cerebral Palsy (CP) have several gait impairments, amongst which impaired gait stability may be one. We tested whether a newly developed stability measure (the foot placement estimator, FPE) which does not require long data series, can be used to asses gait stability in typically developing (TD) children as well as children with CP. In doing so, we tested the FPE’s sensitivity to the assumptions needed to calculate this measure, as well as the ability of the FPE to detect differences in stability between children with CP and TD children, and differences in walking speed. Participants were asked to walk at two different speeds, while gait kinematics were recorded. From these data, the FPE, as well as the error that violations of assumptions of the FPE could have caused were calculated. The results showed that children with CP walked with marked instabilities in anterior-posterior and mediolateral directions. Furthermore, errors caused by violations of assumptions in calculation of FPE were only small (~1.5 cm), while effects of walking speed (~20 cm per m/s increase in walking speed) and group (~5cm) were much larger. These results suggest that the FPE may be used to quantify gait stability in TD children and children with CP. PMID:23500163

Bruijn, Sjoerd M.; Millard, Matthew; van Gestel, Leen; Meyns, Pieter; Jonkers, Ilse; Desloovere, Kaat

2013-01-01

229

Coupled Nonlinear Oscillators and the Symmetries of Animal Gaits  

Microsoft Academic Search

Summary. Animal locomotion typically employs several distinct periodic patterns of leg movements, known as gaits. It has long been observed that most gaits possess a degree of symmetry. Our aim is to draw attention to some remarkable parallels between the generalities of coupled nonlinear oscillators and the observed symmetries of gaits, and to describe how this observation might impose constraints

J. J. Collins; I. N. Stewart

1993-01-01

230

Variation in human gait intervals on a treadmill  

E-print Network

to investigate the dynamics of gait on a stride by stride basis. Typical gait analysis limits study to a single gait cycle. Poincare sections, and bifurcation analyses are useful tools for studying the dynamics of quasi-periodic phenomena. This suggests their use...

Abrams, Mark Alan

1994-01-01

231

A simple method for determination of gait events  

Microsoft Academic Search

Simple and effective methods for determining the timing of gait events are necessary for the proper normalization and statistical analysis of gait data when a variety of gait measurements are available. The approach presented was developed for cases in which overall center of pressure under the body and marker trajectories are being measured over multiple steps. The new method presented

Andrew H. Hansen; Dudley S. Childress; Margrit R. Meier

2002-01-01

232

Gait characteristics in individuals with intellectual disabilities: a literature review.  

PubMed

Gait is a functionally highly relevant aspect of motor performance. In the general population poorer gait increases the risk of falls and is a predictor for future disability, cognitive impairment, institutionalization and/or mortality. People with intellectual disabilities (ID) show a delayed motor development, which brings to attention the abnormalities that might accompany gait in this population throughout childhood and adulthood. Therefore, this paper aims (a) to provide a focused review of the available literature on gait characteristics in individuals with ID and (b) to gain insight into available instrumentations measuring gait in this population. We searched the database of PubMed for relevant articles and the reference lists of included articles, resulting in 44 included articles. Forty one studies reported gait characteristics during over-ground walking and six studies during perturbed walking conditions. Most studies investigated syndrome-specific ID populations, only five studies investigated the general ID population. The studies show that gait abnormalities are evident during over-ground walking in the ID population, both in people with genetic syndromes and with ID without genetic syndromes. During perturbed conditions people with ID altered their gait with stability-enhancing adaptations. Abnormalities in gait may be partly explained by physical features, but the interrelatedness between gait and cognition may also be an explanation for the gait abnormalities seen in the ID population. Further research regarding gait characteristics of the ID population, and its relation to cognitive functioning, and adverse health outcomes is needed. PMID:25105568

Almuhtaseb, Sanaa; Oppewal, Alyt; Hilgenkamp, Thessa I M

2014-11-01

233

A Survey of Silhouette-Based Gait Recognition Methods  

E-print Network

A Survey of Silhouette-Based Gait Recognition Methods Craig Martek, cmm6857@rit.edu Abstract Gait of some recent gait recognition methods based on the silhouette images acquired from a sequence to three dimensions. Motion-based approaches often operate on the silhouettes of a subject, which can

Zanibbi, Richard

234

Effect of silhouette quality on hard problems in gait recognition  

Microsoft Academic Search

Gait as a behavioral biometric has been the subject of recent investigations. However, understanding the limits of gait-based recognition and the quantitative study of the factors effecting gait have been confounded by errors in the extracted silhouettes, upon which most recognition algorithms are based. To enable us to study this effect on a large population of subjects, we present a

Zongyi Liu; Sudeep Sarkar

2005-01-01

235

Gait Characterization via Pulse-Doppler Radar Tarik Yardibi  

E-print Network

risk in elderly people [1]: i) mean gait velocity, ii) gait velocity variability, iii) mean strideGait Characterization via Pulse-Doppler Radar Tarik Yardibi * , Paul Cuddihy * , Sahika Genc of Nursing, Columbia, MO Abstract Falls are a major cause of injury in the elderly with almost 1/3 rd

He, Zhihai "Henry"

236

Understanding Ageing Effects by Approximate Entropy Analysis of gait variability  

Microsoft Academic Search

Ageing influences gait patterns which in turn affects the control mechanism of human locomotor balance. The aim of this study is to investigate the relationship between approximate entropy (ApEn) and standard deviation (SD) of a gait variable (minimum toe clearance, MTC) for young and elderly gait patterns. MTC data of 30 healthy young (HY), 27 healthy elderly (HE) and 10

Chandan K. Karmakar; Ahsan H. Khandoker; Rezaul K. Begg; Marimuthu Palaniswami; S. Taylor

2007-01-01

237

Gait assessment for elderly using a portable acceleration monitoring device  

Microsoft Academic Search

This study developed a portable acceleration monitoring device for gait assessments, and applied it to assess the gait of elderly. In a gait assessment experiment, 21 elderly subjects, wearing the portable acceleration monitoring device on their lower backs, walked on a test track. Four sets of evaluation indexes (physical activity, stability, symmetry, average speed) were derived from the acceleration data

Naruhiro SHIOZAWA; Shima OKADA; Masaaki MAKIKAWA

2010-01-01

238

Human Odometry Verifies the Symmetry Perspective on Bipedal Gaits  

ERIC Educational Resources Information Center

Bipedal gaits have been classified on the basis of the group symmetry of the minimal network of identical differential equations (alias "cells") required to model them. Primary gaits are characterized by dihedral symmetry, whereas secondary gaits are characterized by a lower, cyclic symmetry. This fact was used in a test of human odometry. Results…

Turvey, M. T.; Harrison, Steven J.; Frank, Till D.; Carello, Claudia

2012-01-01

239

Dynamic Analysis of Human Gait Disorder and Metabolical Cost Estimation  

Microsoft Academic Search

For the design and improvement of orthotic and prosthetic devices the biomechanical effort is an important criterion to obtain a more comfortable and natural gait of humans with gait disorders. In the first part of the paper the inverse dynamic analysis based on measurements of the human gait for subjects with different kinds of disorders is presented. The second part

Marko Ackermann; Werner Schiehlen

2006-01-01

240

Polar Bear  

NSDL National Science Digital Library

In this episode of the Podcast of Life, host Ari Daniel Shapiro relates two close calls with polar bears. Listen as Heather Cray recalls how, dumped by a storm on a small Arctic island without a shotgun, she got an unexpected wake-up call. And when researcher Steve Amstrup accidentally crashed through the roof of a polar bearâs den, no one could predict what happened next. Also included is a Learn More section that provides background information on the scientists recorded in the podcast, lessons, images, and cool facts.

2009-01-01

241

Freezing of gait in older adults with high level gait disorders: association with impaired executive function  

Microsoft Academic Search

Summary  Freezing of gait (FOG) is frequently observed in high level gait disorders (HLGD), but its relationship to disease progression\\u000a and cognitive function is unknown. To study this relationship, episodic gait disturbances, affect and cognitive function were\\u000a assessed in twenty-five patients with HLGD (mean age: 78.2 ± 5.0?yrs). After a mean of 32.2 ± 4.2 months, twenty-two patients\\u000a were reassessed. FOG

N. Giladi; V. Huber-Mahlin; T. Herman; J. M. Hausdorff

2007-01-01

242

Evaluation of gait with multichannel electrical stimulation.  

PubMed

Short, intensive multichannel electrical stimulation therapy was evaluated in 14 hemiplegics after stroke or head injury. The stimulation of the peroneal nerve, soleus, quadriceps, hamstring, gluteus maximus, and triceps brachii muscles with individually preprogrammed sequences was applied by surface electrodes at the beginning of gait rehabilitation. The patients started walking with the support of a therapist, gradually increased the walking distance and all reached independent ambulation with a crutch after an average of 14 stimulation sessions. A portable microprocessor six-channel stimulator/stride analyzer enabled the collection of gait parameters and recording of statistical mean values of stride time, gait symmetry, right and left stance times, and their standard deviations. Without additional equipment, several hundred stimulated strides were measured during each stimulation session. PMID:3495792

Malezic, M; Bogataj, U; Gros, N; Kelih, B; Kljajic, M; A?imovi?-Janezic, R

1987-05-01

243

Kinematics gait disorder in men with fibromyalgia.  

PubMed

The aim of this study was to assess the kinematics disorder of gait in men with fibromyalgia. We studied 12 male with fibromyalgia and 14 healthy men. Each participant of the study walked five trials along a 18.6-m walkway. Fibromyalgia patients completed a Spanish version of Fibromyalgia Impact Questionnaire. Significant differences between fibromyalgia and control groups were found in velocity, stride length, and cadence. Gait parameters of men affected by fibromyalgia were impaired when compared to those of healthy group due to bradykinesia. According to previous studies to assess gait variables in female patients, the male with fibromyalgia also showed lower values of velocity, cadence, and stride length than healthy group but not reported significant differences in swing, stance, single, or double support phase. PMID:23292191

Heredia-Jimenez, Jose M; Soto-Hermoso, Victor M

2014-01-01

244

An investigation of gait in children with Attention Deficit Hyperactivity Disorder: a case controlled study.  

PubMed

This study aimed to compare the gait of children with ADHD - Combined Type (ADHD-CT) to typically developing (TD) children. Children with ADHD-CT (n=14; mean age 10 years 4 months) and a TD group (n=13; mean age 10 years 9 months) walked at self-selected slow, preferred and fast speed on an electronic walkway system. Participants completed a total of 15 walking trials; 5 trials per walking condition. Groups were matched on age, intellectual functioning, height and weight. In the preferred walking condition, there was no difference in spatio-temporal gait variables between the ADHD-CT and TD control groups. At self-selected fast speed, children with ADHD-CT were faster and walked with a higher cadence. The subtle alterations in gait pattern that may reflect a timing deficit is consistent with previous ADHD motor studies. In addition, this study extends previous studies in characterising the unique gait profile of non-medicated children with ADHD-CT where a diagnosis of autism spectrum disorder has been ruled out. PMID:24837426

Papadopoulos, Nicole; McGinley, Jennifer L; Bradshaw, John L; Rinehart, Nicole J

2014-08-30

245

Biped gait stabilization via foot placement.  

PubMed

It is shown that stable biped gaits can be achieved by discrete foot placement based on feedback of information available at the time of foot placement. The model, developed by Townsend (1981, J. Biomechanics 14, p. 727) to evaluate the coordinations of torso motions, subsumes most of the salient body members and motions. The modeling yielded a generalized inverted pendulum with a movable support point which physically defines lateral foot placement. The principal result is that stable gaits can be defined by foot placements which are a linear function of the system center of mass position and velocity at the time of foot placement (only). Gaits may be 'smooth' or may have impulsive corrections to adjust the character of the motions and foot placement. Several general algorithms and specific simulations are presented, and calculations for non-impulsive gaits and impulsive corrections are presented. The model predictions are compared with published data. The predictions are sufficiently close to the data such that the general algorithms appear to be validated. Of particular interest are the non-sinusoidal character of the motions and the relatively simple algorithms. Indeed, the simplicity of the algorithms suggests the practical possibility of legged mobile robots. Accordingly, further investigation seems warranted for determining the parametric variation and control of gait. Some attention is also given to continuous-feedback control such as would exist during double-leg support and in specialized tasks such as rope walking or skating. Subsequent investigation will consider superposition of single and double leg support, although clearly the discrete gaits pose the more restrictive stability problem. PMID:3980486

Townsend, M A

1985-01-01

246

Development of gait training system powered by pneumatic actuator like human musculoskeletal system.  

PubMed

The purpose of this study was to develop a body weight support gait training system for stroke and spinal cord injury (SCI) patient. This system consists of an orthosis powered by pneumatic McKibben actuators and a piece of equipment of body weight support. The attachment of powered orthosis can be fit to individual subjects with different body size. This powered orthosis is driven by pneumatic McKibben actuators arranged as a pair of agonistic and antagonistic bi-articular muscle models and two pairs of agonistic and antagonistic mono-articular muscle models like the human musculoskeletal system. The body weight support equipment suspends the subject's body in a wire harness, with the body weight is supported continuously by a counterweight. The powered orthosis is attached to the body weight support equipment by a parallel linkage, and its movement of powered orthosis is limited at the sagittal plane. The weight of the powered orthosis is compensated by a parallel linkage with a gas-spring. In this paper, we report the detailed mechanics of this body weight support gait training system and the results of several experiments for evaluating the system. PMID:22275650

Yamamoto, Shin-ichiroh; Shibata, Yoshiyuki; Imai, Shingo; Nobutomo, Tatsuya; Miyoshi, Tasuku

2011-01-01

247

Fluctuation and synchronization of gait intervals and gait force profiles distinguish stages of Parkinson's disease  

NASA Astrophysics Data System (ADS)

We study the effects of Parkinson's disease (PD) on the long-term fluctuation and phase synchronization properties of gait timing (series of interstride intervals) as well as gait force profiles (series characterizing the morphological changes between the steps). We find that the fluctuations in the gait timing are significantly larger for PD patients and early PD patients, who were not treated yet with medication, compared to age-matched healthy controls. Simultaneously, the long-term correlations and the phase synchronization of right and left leg are significantly reduced in both types of PD patients. Surprisingly, long-term correlations of the gait force profiles are relatively weak for treated PD patients and healthy controls, while they are significantly larger for early PD patients. The results support the idea that timing and morphology of recordings obtained from a complex system can contain complementary information.

Bartsch, Ronny; Plotnik, Meir; Kantelhardt, Jan W.; Havlin, Shlomo; Giladi, Nir; Hausdorff, Jeffrey M.

2007-09-01

248

Kinetic changes in gait during low magnitude military load carriage.  

PubMed

Indian infantry soldiers carry smaller magnitudes of loads for operational requirements. The ground reaction forces (GRFs) and impulse responses of 10 healthy male Indian infantry soldiers were collected while they walked carrying operational loads between 4.2 and 17.5 kg (6.5-27.2% of mean body weight (BW)) and a control condition of no external load (NL). The GRF and impulse components were normalised for BW, and data for each load condition were compared with NL in each side applying one-way analysis of variance followed by Dunnett's post hoc test. Right foot data were compared with corresponding left foot GRF data for all load conditions and NL. There were significant increases in vertical and anteroposterior GRFs with increase in load. Left and right feet GRF data in corresponding load conditions were significantly different in anteroposterior plane. No significant change was observed in the temporal components of support phase of gait. Changes in impulse parameter were observed in the anteroposterior and vertical planes while carrying load greater than 23 and 16.6% of BW for the right foot and left foot, respectively. Result indicates that smaller magnitudes of loads produced kinetic changes proportional to system weight, similar to heavier loads with the possibility of increased injury risk. Observed smaller asymmetric changes in gait may be considered as postural adjustment due to load. Unique physical characteristics of Indian soldiers and the probable design shortcomings of the existing backpack might have caused significant changes in GRF and peak impulse during smaller load carriage. PMID:24164415

Majumdar, Deepti; Pal, Madhu Sudan; Pramanik, Anilendu; Majumdar, Dhurjati

2013-01-01

249

Ratite Footprints and the Stance and Gait  

E-print Network

footprints of the Mesozoic Era attributed to theropod dinosaurs. Of par- ticular interest,'(i) the rheaRatite Footprints and the Stance and Gait of Mesozoic Theropods KEVIN PADIAN AND PAUL E. OLSEN, and the toes and claws leave no drag marks. These are all characteristic of Mesozoic theropod (and ornithopod

Olsen, Paul E.

250

Data processing for posturography and gait analysis  

Microsoft Academic Search

The aim of this study is to develop a system for extracting information during postural stability tests, using a new capacitive force sensor conceived and made by us. Based on the capacitive force sensor, we developed a pedometric force plate (PFP) for use in human postural and gait analysis. We present the method of data acquisition, the signal processing and

Marius Hagan; Horia-Nicolai Teodorescu; Adriana Sîrbu

2010-01-01

251

Gait intiation in bilateral vestibular loss  

Microsoft Academic Search

Objective: Gait initiation is a transient procedure between orthostatic posture and steady-state locomotion and includes anticipatory anteroposterior (AP) and lateral movements. Commands for this task are located in some levels of brain stem, which modulates activity of central pattern generator in the spinal cord. The purpose of this work was to explore the role of the vestibular system in this

Osamu Sasaki; Shiro Asawa; Satoshi Katsuno; Shin-ichi Usami; Kiichiro Taguchi

2001-01-01

252

Gait analysis and validation using voxel data  

Microsoft Academic Search

In this paper, we present a method for extracting gait parameters including walking speed, step time and step length from a three-dimensional voxel reconstruction, which is built from two calibrated camera views. These parameters are validated with a GAITRite Electronic mat and a Vicon motion capture system. Experiments were conducted in which subjects walked across the GAITRite mat at various

Fang Wang; Erik Stone; Wenqing Dai; Marjorie Skubic; James Keller

2009-01-01

253

A practical gait analysis system using gyroscopes  

Microsoft Academic Search

This study investigated the possibility of using uni-axial gyroscopes to develop a simple portable gait analysis system. Gyroscopes were attached on the skin surface of the shank and thigh segments and the angular velocity for each segment was recorded in each segment. Segment inclinations and knee angle were derived from segment angular velocities. The angular signals from a motion analysis

Kaiyu Tong; Malcolm H Granat

1999-01-01

254

ORIGINAL ARTICLE Prevalence of Specific Gait Abnormalities  

E-print Network

ORIGINAL ARTICLE Prevalence of Specific Gait Abnormalities in Children With Cerebral Palsy Influence of Cerebral Palsy Subtype, Age, and Previous Surgery Tishya A. L. Wren, PhD,* Susan Rethlefsen, PT. These findings provide important information for counsel- ing ambulatory children with cerebral palsy

Valero-Cuevas, Francisco

255

Unrestraint support robot for elderly gait rehabilitation  

Microsoft Academic Search

This paper presents a prototype development of an unrestraint support robot for gait rehabilitation of injured or elderly people. Our developed system consists of a support robot for preventing a trainee from falling with bodily unrestraint. Unrestraint means not atattching markers or sensors on the body, but using an optical sensor for detecting a position of the trainee and a

Makoto Nokata; Wataru Hirai

2009-01-01

256

Comparison of Gait Aspects According to FES Stimulation Position Applied to Stroke Patients  

PubMed Central

[Purpose] This study sought to identify the gait aspects according to the FES stimulation position in stroke patients during gait training. [Subjects and Methods] To perform gait analysis, ten stroke patients were grouped based on 4 types of gait conditions: gait without FES stimulation (non-FES), gait with FES stimulation on the tibialis anterior (Ta), gait with FES stimulation on the tibialis anterior and quadriceps (TaQ), and gait with FES stimulation on the tibialis anterior and gluteus medius (TaGm). [Results] Based on repeated measures analysis of variance of measurements of gait aspects comprised of gait speed, gait cycle, and step length according to the FES stimulation position, the FES stimulation significantly affected gait aspects. [Conclusion] In conclusion, stimulating the tibialis anterior and quadriceps and stimulating the tibialis anterior and gluteus medius are much more effective than stimulating only the tibialis anterior during gait training in stroke patients using FES. PMID:24764634

Mun, Byeong-mu; Kim, Tae-ho; Lee, Jin-hwan; Lim, Jin-youg; Seo, Dong-kwon; Lee, Dong-jin

2014-01-01

257

ES and H-compatible lubrication for duplex bearings  

SciTech Connect

Two ES and H-compatible lubricants (environment, safety, and health) for duplex bearing applications and one hybrid material duplex bearing were evaluated and compared against duplex bearings with trichlorotrifluoroethane (Freon) deposition of low molecular weight polytetrafluoroethylene (PTFE) bearing lubricant extracted from Vydax{trademark}. Vydax is a product manufactured by DuPont consisting of various molecular weights of PTFE suspended in trichlorotrifluoroethane (Freon), which is an ozone-depleting solvent. Vydax has been used as a bearing lubricant in strong link mechanisms since 1974. Hybrid duplex bearings with silicon nitride balls and molded glass-nylon-Teflon retainers, duplex bearings lubricated with sputtered MoS{sub 2} on races and retainers, and duplex bearings lubricated with electrophoretic deposited MoS{sub 2} were evaluated. Bearings with electrophoretic deposited MoS{sub 2} performed as well as bearings with Freon deposition of PTFE from Freon-based Vydax. Hybrid bearings with silicon nitride balls performed worse than bearings lubricated with Vydax, but their performance would still be acceptable for most applications. Bearings lubricated with sputtered MoS{sub 2} on the races and retainers had varying amounts of film on the bearings. This affected the performance of the bearings. Bearings with a uniform coating performed to acceptable levels, but bearings with no visible MoS{sub 2} on the races and retainers did not perform as well as bearings with the other coatings. Unless process controls are incorporated in the sputtering process or the bearings are screened, they do not appear to be acceptable for duplex bearing applications.

Steinhoff, R.G.

1997-10-01

258

Gait recognition based on Kinect sensor  

NASA Astrophysics Data System (ADS)

This paper presents gait recognition based on human skeleton and trajectory of joint points captured by Microsoft Kinect sensor. In this paper Two sets of dynamic features are extracted during one gait cycle: the first is Horizontal Distance Features (HDF) that is based on the distances between (Ankles, knees, hands, shoulders), the second set is the Vertical Distance Features (VDF) that provide significant information of human gait extracted from the height to the ground of (hand, shoulder, and ankles) during one gait cycle. Extracting these two sets of feature are difficult and not accurate based on using traditional camera, therefore the Kinect sensor is used in this paper to determine the precise measurements. The two sets of feature are separately tested and then fused to create one feature vector. A database has been created in house to perform our experiments. This database consists of sixteen males and four females. For each individual, 10 videos have been recorded, each record includes in average two gait cycles. The Kinect sensor is used here to extract all the skeleton points, and these points are used to build up the feature vectors mentioned above. K-nearest neighbor is used as the classification method based on Cityblock distance function. Based on the experimental result the proposed method provides 56% as a recognition rate using HDF, while VDF provided 83.5% recognition accuracy. When fusing both of the HDF and VDF as one feature vector, the recognition rate increased to 92%, the experimental result shows that our method provides significant result compared to the existence methods.

Ahmed, Mohammed; Al-Jawad, Naseer; Sabir, Azhin T.

2014-05-01

259

Intersegmental coordination of gait after hemorrhagic stroke.  

PubMed

We compared gait using the planar law of intersegmental coordination between 14 hemorrhagic stroke subjects walking at a self-selected normal speed (56 ± 21 cm/s) and 15 age-matched healthy controls walking at a very slow speed (56 ± 19 cm/s). Sagittal plane elevation angles of the thigh, shank, and foot segments were submitted to principal component analysis. Additional outcome measures included the range of elevation angle and timing of peak elevation angle of the thigh, shank, and foot segments. The range of elevation angles at the shank and foot was significantly smaller in the paretic leg than non-paretic and control legs. Also, the peak elevation angle at the thigh occurred significantly later in the gait cycle in the paretic than control leg. Gait of both stroke and control subjects followed the planar law with the first two principal components explaining approximately 99 % of the variance. However, the three-dimensional trajectory of elevation angles (gait loop) in stroke subjects deviated from the typical teardrop shape bilaterally, which was more exaggerated in the paretic leg. Compared to the non-paretic and control legs, the paretic leg showed significantly increased absolute loading of the thigh elevation angle and decreased absolute loadings of the shank and foot elevation angles on the first principal component, whereas the opposite was observed for the second principal component. Despite following the planar law, the gait of chronic stroke subjects is characterized by atypical timing of the thigh motion and disrupted intersegmental coordination of both legs. PMID:25224705

Chow, John W; Stokic, Dobrivoje S

2015-01-01

260

A new intelligent model for automated assessment of elder gait change  

Microsoft Academic Search

This paper addressed a novel intelligent model for automatic evaluation of the change of elder gait function based on kinematic gait data. In order to recognize the change of elderly gait patterns with higher accuracy, the wavelet analysis technique was proposed as a new approach to extract gait features, and then those obtained gait features were initiated the training set

Jianning Wu

2010-01-01

261

The effect of kinematic and kinetic changes on meniscal strains during gait.  

PubMed

The menisci play an important role in load distribution, load bearing, joint stability, lubrication, and proprioception. Partial meniscectomy has been shown to result in changes in the kinematics and kinetics at the knee during gait that can lead to progressive meniscal degeneration. This study examined changes in the strains within the menisci associated with kinematic and kinetic changes during the gait cycle. The gait changes considered were a 5 deg shift toward external rotation of the tibia with respect to the femur and an increased medial-lateral load ratio representing an increased adduction moment. A finite element model of the knee was developed and tested using a cadaveric specimen. The cadaver was placed in positions representing heel-strike and midstance of the normal gait, and magnetic resonance images were taken. Comparisons of the model predictions to boundaries digitized from images acquired in the loaded states were within the errors produced by a 1 pixel shift of either meniscus. The finite element model predicted that an increased adduction moment caused increased strains of both the anterior and posterior horns of the medial meniscus. The lateral meniscus exhibited much lower strains and had minimal changes under the various loading conditions. The external tibial rotational change resulted in a 20% decrease in the strains in the posterior medial horn and increased strains in the anterior medial horn. The results of this study suggest that the shift toward external tibial rotation seen clinically after partial medial meniscectomy is not likely to cause subsequent degenerative medial meniscal damage, but the consequence of this kinematic shift on the pathogenesis of osteoarthritis following meniscectomy requires further consideration. PMID:21186896

Netravali, Nathan A; Koo, Seungbum; Giori, Nicholas J; Andriacchi, Thomas P

2011-01-01

262

Optimal Synchronizability of Bearings  

E-print Network

Bearings are mechanical dissipative systems that, when perturbed, relax toward a synchronized (bearing) state. Here we find that bearings can be perceived as physical realizations of complex networks of oscillators with ...

Seybold, Hansjorg

263

Lubricant replacement in rolling element bearings for weapon surety devices  

SciTech Connect

Stronglink switches are a weapon surety device that is critical to the nuclear safety theme in modem nuclear weapons. These stronglink switches use rolling element bearings which contain a lubricant consisting of low molecular weight polytetrafluoroethylene (PTFE) fragments. Ozone-depleting solvents are used in both the manufacture and application of this lubricant. An alternate bearing lubrication for stronglink switches is needed that will provide long-term chemical stability, low migration and consistent performance. Candidates that were evaluated include bearings with sputtered MoS{sub 2} on the races and retainers, bearings with TiC-coated balls, and bearings with Si{sub 3}N{sub 4} balls and steel races. These candidates were compared to the lubricants currently used which are bearings lubricated with PTFE fragments of low molecular weight in a fluorocarbon solvent. The candidates were also compared to bearings lubricated with a diester oil which is representative of bearing lubricants used in industrial applications. Evaluation consisted of cycling preloaded bearings and subjecting them to 23 gRMS random vibration. All of the candidates are viable substitutes for low load application where bearing preload is approximately 1 pound. For high load applications where the bearing preload is approximately 10 pounds, bearings with sputtered MoS{sub 2} on the races and retainers appear to be the best substitutes. Bearings with TiC-coated balls also appear to be a viable candidate but these bearings did not perform as well as the sputtered MoS{sub 2}.

Steinhoff, R.; Dugger, M.T.; Varga, K.S. [Sandia National Laboratories, Albuquerque, NM (United States)

1996-05-01

264

Muscle strength training to improve gait function in children with cerebral palsy.  

PubMed

The aim of the study was to investigate the influence of muscle strength training on gait outcomes in children with cerebral palsy. Sixteen children (two females, 14 males, Gross Motor Function Classification System levels I-II, mean age 12y 6mo, range 9y 4mo-15y 4mo) underwent muscle strength measurement using a handheld device, Gross Motor Function Measure (GMFM) assessment, three-dimensional gait analysis, joint range of motion assessment, and grading of spasticity before and after 8 weeks of training. All participants had a diagnosis of spastic diplegia and could walk without aids. Training consisted of exercises for lower extremity muscles with free weights, rubber bands, and body weight for resistance, three times a week. Values for muscle strength below normal were identified in all children; this was most pronounced at the ankle, followed by the hip muscles. After training, muscle strength and GMFM scores increased, velocity was unchanged, stride length increased, and cadence was reduced. There was an increase in hip extensor moment and power generated at push off. Eight weeks of muscle strength training can increase muscle strength and improve gait function. PMID:18834389

Eek, Meta Nyström; Tranberg, Roy; Zügner, Roland; Alkema, Kristina; Beckung, Eva

2008-10-01

265

Design and test of a magnetic thrust bearing  

NASA Technical Reports Server (NTRS)

A magnetic thrust bearing can be employed to take thrust loads in rotating machinery. The design and construction of a prototype magnetic thrust bearing for a high load per weight application is described. The theory for the bearing is developed. Fixtures were designed and the bearing was tested for load capacity using a universal testing machine. Various shims were employed to have known gap thicknesses. A comparison of the theory and measured results is presented.

Allaire, P. E.; Mikula, A.; Banerjee, B.; Lewis, D. W.; Imlach, J.

1993-01-01

266

Gait and upper limb variability in Parkinson's disease patients with and without freezing of gait.  

PubMed

Patients with Parkinson's disease (PD) and freezing of gait (FOG) (freezers) demonstrate high gait variability. The objective of this study was to determine whether freezers display a higher variability of upper limb movements and elucidate if these changes correlate with gait. We were the first group to compare directly objectively measured gait and upper limb movement variability of freezers between freezing episodes. Patients with objectively verified FOG (n = 11) and PD patients without FOG (non-freezers) (n = 11) in a non-randomized medication condition (OFF/ON) were analyzed. Uncued antiphasic finger tapping and forearm diadochokinetic movements were analyzed via three-dimensional ultrasound kinematic measurements. Gait variability of straight gait was assessed using ground reaction forces. Freezers had shorter stride length (p = 0.004) and higher stride length variability (p = 0.005) in the medication OFF condition. Movement variability was not different during finger tapping or diadochokinesia between the groups. There was a trend towards more freezing of the upper limb during finger tapping for the freezers (p = 0.07). Variability in stride length generation and stride timing was not associated with variability of upper limb movement in freezers. Our findings demonstrate that: (1) freezers have a higher spatial gait variability between freezing episodes; (2) freezing-like episodes of the upper limb occur in PD patients, and tend to be more pronounced among freezers than non-freezers for finger tapping; (3) spatial and temporal upper extremity variability is equally affected in freezers and non-freezers in an uncued task. Upper limb freezing is not correlated to lower limb freezing, implicating a different pathophysiology. PMID:24305993

Barbe, Michael T; Amarell, Martin; Snijders, Anke H; Florin, Esther; Quatuor, Eva-Lotte; Schönau, Eckhard; Fink, Gereon R; Bloem, Bastiaan R; Timmermann, Lars

2014-02-01

267

Kinematic Analysis Quantifies Gait Abnormalities Associated with Lameness in Broiler Chickens and Identifies Evolutionary Gait Differences  

PubMed Central

This is the first time that gait characteristics of broiler (meat) chickens have been compared with their progenitor, jungle fowl, and the first kinematic study to report a link between broiler gait parameters and defined lameness scores. A commercial motion-capturing system recorded three-dimensional temporospatial information during walking. The hypothesis was that the gait characteristics of non-lame broilers (n?=?10) would be intermediate to those of lame broilers (n?=?12) and jungle fowl (n?=?10, tested at two ages: immature and adult). Data analysed using multi-level models, to define an extensive range of baseline gait parameters, revealed inter-group similarities and differences. Natural selection is likely to have made jungle fowl walking gait highly efficient. Modern broiler chickens possess an unbalanced body conformation due to intense genetic selection for additional breast muscle (pectoral hypertrophy) and whole body mass. Together with rapid growth, this promotes compensatory gait adaptations to minimise energy expenditure and triggers high lameness prevalence within commercial flocks; lameness creating further disruption to the gait cycle and being an important welfare issue. Clear differences were observed between the two lines (short stance phase, little double-support, low leg lift, and little back displacement in adult jungle fowl; much double-support, high leg lift, and substantial vertical back movement in sound broilers) presumably related to mass and body conformation. Similarities included stride length and duration. Additional modifications were also identified in lame broilers (short stride length and duration, substantial lateral back movement, reduced velocity) presumably linked to musculo-skeletal abnormalities. Reduced walking velocity suggests an attempt to minimise skeletal stress and/or discomfort, while a shorter stride length and time, together with longer stance and double-support phases, are associated with instability. We envisage a key future role for this highly quantitative methodology in pain assessment (associated with broiler lameness) including experimental examination of therapeutic agent efficacy. PMID:22815823

Caplen, Gina; Hothersall, Becky; Murrell, Joanna C.; Nicol, Christine J.; Waterman-Pearson, Avril E.; Weeks, Claire A.; Colborne, G. Robert

2012-01-01

268

Kinematic analysis of mobile-bearing total knee arthroplasty using a 6DOF knee simulator  

Microsoft Academic Search

Background  The purpose of this study was to investigate the kinematics of the polyethylene insert in two designs of mobilebearing total\\u000a knee arthroplasty, using a six-degrees-of-freedom knee simulator. It was consequently not clear whether the motion of the\\u000a polyethylene bearing in mobile-bearing total knee arthroplasty could be demonstrated during the gait cycle or more rapid movement.\\u000a \\u000a \\u000a \\u000a Methods  A mobile-bearing knee (Zimmer) and

Satoshi Hamai; Hiromasa Miura; Hidehiko Higaki; Takeshi Shimoto; Yoshitaka Nakanishi; Yukihide Iwamoto

2008-01-01

269

Gait analysis of a radial symmetrical hexapod robot based on parallel mechanisms  

NASA Astrophysics Data System (ADS)

Most gait studies of multi-legged robots in past neglected the dexterity of robot body and the relationship between stride length and body height. This paper investigates the performance of a radial symmetrical hexapod robot based on the dexterity of parallel mechanism. Assuming the constraints between the supporting feet and the ground with hinges, the supporting legs and the hexapod body are taken as a parallel mechanism, and each swing leg is regarded as a serial manipulator. The hexapod robot can be considered as a series of hybrid serial-parallel mechanisms while walking on the ground. Locomotion performance can be got by analyzing these equivalent mechanisms. The kinematics of the whole robotic system is established, and the influence of foothold position on the workspace of robot body is analyzed. A new method to calculate the stride length of multi-legged robots is proposed by analyzing the relationship between the workspaces of two adjacent equivalent parallel mechanisms in one gait cycle. Referring to service region and service sphere, weight service sphere and weight service region are put forward to evaluate the dexterity of robot body. The dexterity of single point in workspace and the dexterity distribution in vertical and horizontal projection plane are demonstrated. Simulation shows when the foothold offset goes up to 174 mm, the dexterity of robot body achieves its maximum value 0.1644 in mixed gait. The proposed methods based on parallel mechanisms can be used to calculate the stride length and the dexterity of multi-legged robot, and provide new approach to determine the stride length, body height, footholds in gait planning of multi-legged robot.

Xu, Kun; Ding, Xilun

2014-09-01

270

Gait analysis of a radial symmetrical hexapod robot based on parallel mechanisms  

NASA Astrophysics Data System (ADS)

Most gait studies of multi-legged robots in past neglected the dexterity of robot body and the relationship between stride length and body height. This paper investigates the performance of a radial symmetrical hexapod robot based on the dexterity of parallel mechanism. Assuming the constraints between the supporting feet and the ground with hinges, the supporting legs and the hexapod body are taken as a parallel mechanism, and each swing leg is regarded as a serial manipulator. The hexapod robot can be considered as a series of hybrid serial-parallel mechanisms while walking on the ground. Locomotion performance can be got by analyzing these equivalent mechanisms. The kinematics of the whole robotic system is established, and the influence of foothold position on the workspace of robot body is analyzed. A new method to calculate the stride length of multi-legged robots is proposed by analyzing the relationship between the workspaces of two adjacent equivalent parallel mechanisms in one gait cycle. Referring to service region and service sphere, weight service sphere and weight service region are put forward to evaluate the dexterity of robot body. The dexterity of single point in workspace and the dexterity distribution in vertical and horizontal projection plane are demonstrated. Simulation shows when the foothold offset goes up to 174 mm, the dexterity of robot body achieves its maximum value 0.1644 in mixed gait. The proposed methods based on parallel mechanisms can be used to calculate the stride length and the dexterity of multi-legged robot, and provide new approach to determine the stride length, body height, footholds in gait planning of multi-legged robot.

Xu, Kun; Ding, Xilun

2014-08-01

271

The Golden Ratio of Gait Harmony: Repetitive Proportions of Repetitive Gait Phases  

PubMed Central

In nature, many physical and biological systems have structures showing harmonic properties. Some of them were found related to the irrational number ? known as the golden ratio that has important symmetric and harmonic properties. In this study, the spatiotemporal gait parameters of 25 healthy subjects were analyzed using a stereophotogrammetric system with 25 retroreflective markers located on their skin. The proportions of gait phases were compared with ?, the value of which is about 1.6180. The ratio between the entire gait cycle and stance phase resulted in 1.620?±?0.058, that between stance and the swing phase was 1.629?±?0.173, and that between swing and the double support phase was 1.684?±?0.357. All these ratios did not differ significantly from each other (F = 0.870, P = 0.422, repeated measure analysis of variance) or from ? (P = 0.670, 0.820, 0.422, resp., t-tests). The repetitive gait phases of physiological walking were found in turn in repetitive proportions with each other, revealing an intrinsic harmonic structure. Harmony could be the key for facilitating the control of repetitive walking. Harmony is a powerful unifying factor between seemingly disparate fields of nature, including human gait. PMID:23862161

Iosa, Marco; Marchetti, Fabio; Morone, Giovanni; Caltagirone, Carlo; Paolucci, Stefano; Peppe, Antonella

2013-01-01

272

Autonomous Evolution of Dynamic Gaits with Two Quadruped Robots  

NASA Technical Reports Server (NTRS)

A challenging task that must be accomplished for every legged robot is creating the walking and running behaviors needed for it to move. In this paper we describe our system for autonomously evolving dynamic gaits on two of Sony's quadruped robots. Our evolutionary algorithm runs on board the robot and uses the robot's sensors to compute the quality of a gait without assistance from the experimenter. First we show the evolution of a pace and trot gait on the OPEN-R prototype robot. With the fastest gait, the robot moves at over 10/min/min., which is more than forty body-lengths/min. While these first gaits are somewhat sensitive to the robot and environment in which they are evolved, we then show the evolution of robust dynamic gaits, one of which is used on the ERS-110, the first consumer version of AIBO.

Hornby, Gregory S.; Takamura, Seichi; Yamamoto, Takashi; Fujita, Masahiro

2004-01-01

273

RELATIONSHIP OF GAIT AND COGNITION IN THE ELDERLY.  

PubMed

Gait and cognitive impairments in older adults mostly reflect the co-occurrence of two geriatric syndromes linked by common underlying brain substrates and pathologies. Gait control is predominately mediated by frontal subcortical circuits, which overlap with circuits controlling executive control and attention functions. These circuits are vulnerable to multiple age-related pathologies such as ischemia, inflammation, and neurodegeneration, which could ultimately cause cognitive, gait, or combined cognitive and gait impairments. The following review aims to describe various gait and cognitive classifications, gait based phenotypes, common underlying pathological processes, and provide a link between motor and cognitive impairments in an effort to predict the risk of dementia, as well as remediate impairments by applying appropriate interventions. PMID:24349877

Parihar, Raminder; Mahoney, Jeannette R; Verghese, Joe

2013-09-01

274

Hamstring and psoas length of crouch gait in cerebral palsy: a comparison with induced crouch gait in age- and sex-matched controls  

PubMed Central

Background Previous studies have shown that hamstring lengths are often not short in patients with cerebral palsy, which raises concerns over the benefits of distal hamstring lengthening in patients with crouch gait. In this study, the authors measured lengths of hamstrings and psoas muscles in normal subjects mimicking crouch gait and compared these with lengths in cerebral palsy patients with crouch gait. Methods Thirty-six patients with cerebral palsy and crouch gait were included in this study, and in addition, 36 age- and sex-matched normal controls were recruited. Hamstring and psoas muscle lengths in patients were evaluated using gait analysis and interactive musculoskeletal modeling software. Muscle lengths were also measured in the normal control group during normal gait and while mimicking crouch gait, and these were compared with those of cerebral palsy patient with crouch gait. Results No significant differences were observed between maximum hamstring (p=0.810) and maximum psoas (p=0.456) lengths of patients and controls mimicking crouch gait. However, patients showed significantly shorter excursions of hamstring (p=0.022) and psoas (p=0.036) muscles than controls, whereas no significant excursion differences were observed between controls during normal gait and mimicking crouch gait. Conclusions Normal controls mimicking crouch gait and cerebral palsy patients with crouch gait demonstrate similar muscle length patterns. However, mimicked crouch gait did not reproduce the excursion pattern shown by patients with crouch gait, which suggests that reduced hamstring and psoas excursion is an innate characteristic of pathologic crouch gait. PMID:23363928

2013-01-01

275

Gait status 17–26 years after selective dorsal rhizotomy  

Microsoft Academic Search

The purpose of this study was to use three-dimensional gait analysis to describe the gait status of adults with spastic diplegia who underwent selective dorsal rhizotomy (SDR) in childhood. Outcome measures were the gait deviation index (GDI), non-dimensional temporal-distance parameters, and kinematics of the lower limbs.A total of 31 adults with spastic diplegia who had previously undergone SDR were eligible

Nelleke G. Langerak; Nicholas Tam; Christopher L. Vaughan; A. Graham Fieggen; Michael H. Schwartz

276

A wireless gait analysis system by digital textile sensors  

Microsoft Academic Search

This paper studies the feasibility of spatio-temporal gait analysis based upon digital textile sensors. Digitized legs and feet patterns of healthy subjects and their relations with spatio-temporal gait parameters were analyzed. In the first experiment, spatio-temporal gait parameters were determined during over ground walking. In the second experiment, predicted running, backward walking, walking up stairs and walking down stairs parameters

Chang-Ming Yang; Chun-Mei Chou; Jwu-Sheng Hu; Shu-Hui Hung; Chang-Hwa Yang; Chih-Chung Wu; Ming-Yang Hsu; Tsi-Lin Yang

2009-01-01

277

Autonomous Evolution of Gaits with the Sony Quadruped Robot  

Microsoft Academic Search

A trend in robotics is towards legged robots.One of the issues with legged robots is thedevelopment of gaits. Typically gaits are developedmanually. In this paper we reportour results of autonomous evolution of dynamicgaits for the Sony Quadruped Robot.Fitness is determined using the robot's digitalcamera and infrared sensors. Using thissystem we evolve faster dynamic gaits thanpreviously manually developed.1 INTRODUCTIONIn this paper

G. S. Hornby; M. Fujita; S. Takamura

1999-01-01

278

Neurological gait abnormalities and risk of falls in older adults  

Microsoft Academic Search

To estimate the validity of neurological gait evaluations in predicting falls in older adults. We studied 632 adults age 70\\u000a and over (mean age 80.6 years, 62% women) enrolled in the Einstein Aging Study whose walking patterns were evaluated by study\\u000a clinicians using a clinical gait rating scale. Association of neurological gaits and six subtypes (hemiparetic, frontal, Parkinsonian,\\u000a unsteady, neuropathic, and

Joe Verghese; Anne F. Ambrose; Richard B. Lipton; Cuiling Wang

2010-01-01

279

Gait attentional load at different walking speeds.  

PubMed

Gait is an attention-demanding task even in healthy young adults. However, scant evidence exists about the attentional load required at various walking speeds. The aim of this study was to investigate motor-cognitive interference while walking at spontaneous, slow and very slow speed on a treadmill while carrying out a backward counting task, in a group (n=22) of healthy young participants. Cognitive performance was also assessed while sitting. Higher DT cost on the cognitive task was found at spontaneous and very slow walking speed, while at slow walking speed the cognitive task was prioritized with higher DT cost on the motor task. The attentional allocation during DT depends on walking speed with gait prioritization at spontaneous and very slow speed that likely represent more challenging motor conditions. PMID:25270327

Nascimbeni, Alberto; Minchillo, Marco; Salatino, Adriana; Morabito, Ursula; Ricci, Raffaella

2015-01-01

280

Treatment of gait ignition failure with ropinirole.  

PubMed

Gait ignition failure (GIF) is a syndrome characterized by hesitation or inability to initiate gait from a static position. It may occur in a variety of conditions, including normal pressure hydrocephalus, subcortical vascular disease, parkinsonian syndromes and a variety of focal lesions. Previous information on the treatment of GIF has been primarily anecdotal, but there have been a few reports of response to dopamine agonists. We report a 63-year-old man with anoxic encephalopathy who developed GIF nine years after the initial anoxic insult. The patient's GIF responded robustly, albeit transiently, to ropinirole. MRI was unrevealing, but a positron emission tomography scan showed hypometabolism in the deep frontal ACA/MCA watershed area; this may have disconnected the basal ganglia from the motor cortex and/or interrupted dopaminergic mesocortical transmission. Our understanding of the pathophysiology and the treatment of GIF remains limited, but there may be at least a limited therapeutic role for dopamine agonists. PMID:25360234

Cohen-Oram, Alexis N; Stewart, Jonathan T; Bero, Kim; Hoffmann, Michael W

2014-10-01

281

Treatment of Gait Ignition Failure with Ropinirole  

PubMed Central

Gait ignition failure (GIF) is a syndrome characterized by hesitation or inability to initiate gait from a static position. It may occur in a variety of conditions, including normal pressure hydrocephalus, subcortical vascular disease, parkinsonian syndromes and a variety of focal lesions. Previous information on the treatment of GIF has been primarily anecdotal, but there have been a few reports of response to dopamine agonists. We report a 63-year-old man with anoxic encephalopathy who developed GIF nine years after the initial anoxic insult. The patient’s GIF responded robustly, albeit transiently, to ropinirole. MRI was unrevealing, but a positron emission tomography scan showed hypometabolism in the deep frontal ACA/MCA watershed area; this may have disconnected the basal ganglia from the motor cortex and/or interrupted dopaminergic mesocortical transmission. Our understanding of the pathophysiology and the treatment of GIF remains limited, but there may be at least a limited therapeutic role for dopamine agonists. PMID:25360234

Cohen-Oram, Alexis N.; Stewart, Jonathan T.; Bero, Kim; Hoffmann, Michael W.

2014-01-01

282

Gait analysis in patients with idiopathic scoliosis  

Microsoft Academic Search

Introduction The goal of this study was to observe scoliotic subjects during level walking to identify asymmetries—which may be related to a neurological dysfunction or the spinal deformity itself—and to correlate these to the severity of the scoliotic curve. Methods We assessed the gait pattern of ten females (median age 14.4) with idiopathic scoliosis characterised by a left-lumbar and a

Inès A. Kramers-de Quervain; Roland Müller; A. Stacoff; Dieter Grob; Edgar Stüssi

2004-01-01

283

Gait characterization via pulse-Doppler radar  

Microsoft Academic Search

Falls are a major cause of injury in the elderly with almost 1\\/3 rd of people aged 65 and more falling each year (1). This work aims to use gait measurements from everyday living environments to estimate risk of falling and enable improved interventions. For this purpose, we consider the use of low-cost pulse-Doppler range control radar. These radars can

Tarik Yardibi; Paul Cuddihy; Sahika Genc; Corey Bufi; Marjorie Skubic; Marilyn Rantz; Liang Liu; Calvin Phillips II

2011-01-01

284

Getting Your Bearings  

NSDL National Science Digital Library

In this activity, learners explore the concept of friction and how ball bearings reduce friction. Learners investigate different uses for ball bearings, how the design has changed over time to incorporate roller bearings, test friction using marbles, and identify the use of ball bearings in everyday items.

IEEE

2013-08-30

285

Passive magnetic bearing configurations  

DOEpatents

A journal bearing provides vertical and radial stability to a rotor of a passive magnetic bearing system when the rotor is not rotating and when it is rotating. In the passive magnetic bearing system, the rotor has a vertical axis of rotation. Without the journal bearing, the rotor is vertically and radially unstable when stationary, and is vertically stable and radially unstable when rotating.

Post, Richard F. (Walnut Creek, CA)

2011-01-25

286

Bearings for Your Whirligig  

NSDL National Science Digital Library

Experiment with friction and make bearings for a whirligig! This activity is a nice introduction to friction and bearings and demonstrates why bearings are useful for spinning. A related video show Vollis Simpson, an artist who creates kinetic sculptures and whirligigs, explain how he uses bearings in all of his spinning pieces so that they move smoothly.

Science Musuem of Minnesota

1995-01-01

287

Restoration of bearings  

NASA Technical Reports Server (NTRS)

Process consisting of grinding raceways to oversize but original quality condition and installing new oversize balls or bearings restores wornout ball and roller bearings to original quality, thereby doubling their operating life. Evaluations reveal process results in restoration of 90% of replaced bearings at less than 50% of new-bearing costs.

Parker, R. J.; Zaretsky, E. V.; Hanau, H.

1977-01-01

288

Cognitive Contributions to Gait and Falls: Evidence and Implications  

PubMed Central

Dementia and gait impairments often coexist in older adults and patients with neurodegenerative disease. Both conditions represent independent risk factors for falls. The relationship between cognitive function and gait has recently received increasing attention. Gait is no longer considered merely automated motor activity but rather an activity that requires executive function and attention as well as judgment of external and internal cues. In this review, we intend to: (1) summarize and synthesize the experimental, neuropsychological, and neuroimaging evidence that supports the role played by cognition in the control of gait; and (2) briefly discuss the implications deriving from the interplay between cognition and gait. In recent years, the dual task paradigm has been widely used as an experimental method to explore the interplay between gait and cognition. Several neuropsychological investigations have also demonstrated that walking relies on the use of several cognitive domains, including executive-attentional function, visuospatial abilities, and even memory resources. A number of morphological and functional neuroimaging studies have offered additional evidence supporting the relationship between gait and cognitive resources. Based on the findings from 3 lines of studies, it appears that a growing body of evidence indicates a pivotal role of cognition in gait control and fall prevention. The interplay between higher-order neural function and gait has a number of clinical implications, ranging from integrated assessment tools to possible innovative lines of interventions, including cognitive therapy for falls prevention on one hand and walking program for reducing dementia risk on the other. PMID:24132840

Amboni, Marianna; Barone, Paolo; Hausdorff, Jeffrey M.

2014-01-01

289

Managing variability in the summary and comparison of gait data  

PubMed Central

Variability in quantitative gait data arises from many potential sources, including natural temporal dynamics of neuromotor control, pathologies of the neurological or musculoskeletal systems, the effects of aging, as well as variations in the external environment, assistive devices, instrumentation or data collection methodologies. In light of this variability, unidimensional, cycle-based gait variables such as stride period should be viewed as random variables and prototypical single-cycle kinematic or kinetic curves ought to be considered as random functions of time. Within this framework, we exemplify some practical solutions to a number of commonly encountered analytical challenges in dealing with gait variability. On the topic of univariate gait variables, robust estimation is proposed as a means of coping with contaminated gait data, and the summary of non-normally distributed gait data is demonstrated by way of empirical examples. On the summary of gait curves, we discuss methods to manage undesirable phase variation and non-robust spread estimates. To overcome the limitations of conventional comparisons among curve landmarks or parameters, we propose as a viable alternative, the combination of curve registration, robust estimation, and formal statistical testing of curves as coherent units. On the basis of these discussions, we provide heuristic guidelines for the summary of gait variables and the comparison of gait curves. PMID:16053523

Chau, Tom; Young, Scott; Redekop, Sue

2005-01-01

290

Dynamic principles of gait and their clinical implications.  

PubMed

A healthy gait pattern depends on an array of biomechanical features, orchestrated by the central nervous system for economy and stability. Injuries and other pathologies can alter these features and result in substantial gait deficits, often with detrimental consequences for energy expenditure and balance. An understanding of the role of biomechanics in the generation of healthy gait, therefore, can provide insight into these deficits. This article examines the basic principles of gait from the standpoint of dynamic walking, an approach that combines an inverted pendulum model of the stance leg with a pendulum model of the swing leg and its impact with the ground. The heel-strike at the end of each step has dynamic effects that can contribute to a periodic gait and its passive stability. Biomechanics, therefore, can account for much of the gait pattern, with additional motor inputs that are important for improving economy and stability. The dynamic walking approach can predict the consequences of disruptions to normal biomechanics, and the associated observations can help explain some aspects of impaired gait. This article reviews the basic principles of dynamic walking and the associated experimental evidence for healthy gait and then considers how the principles may be applied to clinical gait pathologies. PMID:20023002

Kuo, Arthur D; Donelan, J Maxwell

2010-02-01

291

Rolling-Element Bearings  

NASA Technical Reports Server (NTRS)

Rolling element bearings are a precision, yet simple, machine element of great utility. A brief history of rolling element bearings is reviewed and the type of rolling element bearings, their geometry and kinematics, as well as the materials they are made from and the manufacturing processes they involve are described. Unloaded and unlubricated rolling element bearings, loaded but unlubricated rolling element bearings and loaded and lubricated rolling element bearings are considered. The recognition and understanding of elastohydrodynamic lubrication covered, represents one of the major development in rolling element bearings.

Hamrock, B. J.; Anderson, W. J.

1983-01-01

292

Evaluating alternative gait strategies using evolutionary robotics.  

PubMed

Evolutionary robotics is a branch of artificial intelligence concerned with the automatic generation of autonomous robots. Usually the form of the robot is predefined and various computational techniques are used to control the machine's behaviour. One aspect is the spontaneous generation of walking in legged robots and this can be used to investigate the mechanical requirements for efficient walking in bipeds. This paper demonstrates a bipedal simulator that spontaneously generates walking and running gaits. The model can be customized to represent a range of hominoid morphologies and used to predict performance parameters such as preferred speed and metabolic energy cost. Because it does not require any motion capture data it is particularly suitable for investigating locomotion in fossil animals. The predictions for modern humans are highly accurate in terms of energy cost for a given speed and thus the values predicted for other bipeds are likely to be good estimates. To illustrate this the cost of transport is calculated for Australopithecus afarensis. The model allows the degree of maximum extension at the knee to be varied causing the model to adopt walking gaits varying from chimpanzee-like to human-like. The energy costs associated with these gait choices can thus be calculated and this information used to evaluate possible locomotor strategies in early hominids. PMID:15198699

Sellers, William I; Dennis, Louise A; W -J, Wang; Crompton, Robin H

2004-05-01

293

Gait Correlation Analysis Based Human Identification  

PubMed Central

Human gait identification aims to identify people by a sequence of walking images. Comparing with fingerprint or iris based identification, the most important advantage of gait identification is that it can be done at a distance. In this paper, silhouette correlation analysis based human identification approach is proposed. By background subtracting algorithm, the moving silhouette figure can be extracted from the walking images sequence. Every pixel in the silhouette has three dimensions: horizontal axis (x), vertical axis (y), and temporal axis (t). By moving every pixel in the silhouette image along these three dimensions, we can get a new silhouette. The correlation result between the original silhouette and the new one can be used as the raw feature of human gait. Discrete Fourier transform is used to extract features from this correlation result. Then, these features are normalized to minimize the affection of noise. Primary component analysis method is used to reduce the features' dimensions. Experiment based on CASIA database shows that this method has an encouraging recognition performance. PMID:24592144

2014-01-01

294

Gait patterns for crime fighting: statistical evaluation  

NASA Astrophysics Data System (ADS)

The criminality is omnipresent during the human history. Modern technology brings novel opportunities for identification of a perpetrator. One of these opportunities is an analysis of video recordings, which may be taken during the crime itself or before/after the crime. The video analysis can be classed as identification analyses, respectively identification of a person via externals. The bipedal locomotion focuses on human movement on the basis of their anatomical-physiological features. Nowadays, the human gait is tested by many laboratories to learn whether the identification via bipedal locomotion is possible or not. The aim of our study is to use 2D components out of 3D data from the VICON Mocap system for deep statistical analyses. This paper introduces recent results of a fundamental study focused on various gait patterns during different conditions. The study contains data from 12 participants. Curves obtained from these measurements were sorted, averaged and statistically tested to estimate the stability and distinctiveness of this biometrics. Results show satisfactory distinctness of some chosen points, while some do not embody significant difference. However, results presented in this paper are of initial phase of further deeper and more exacting analyses of gait patterns under different conditions.

Sulovská, Kate?ina; B?lašková, Silvie; Adámek, Milan

2013-10-01

295

Gait Signal Analysis with Similarity Measure  

PubMed Central

Human gait decision was carried out with the help of similarity measure design. Gait signal was selected through hardware implementation including all in one sensor, control unit, and notebook with connector. Each gait signal was considered as high dimensional data. Therefore, high dimensional data analysis was considered via heuristic technique such as the similarity measure. Each human pattern such as walking, sitting, standing, and stepping up was obtained through experiment. By the results of the analysis, we also identified the overlapped and nonoverlapped data relation, and similarity measure analysis was also illustrated, and comparison with conventional similarity measure was also carried out. Hence, nonoverlapped data similarity analysis provided the clue to solve the similarity of high dimensional data. Considered high dimensional data analysis was designed with consideration of neighborhood information. Proposed similarity measure was applied to identify the behavior patterns of different persons, and different behaviours of the same person. Obtained analysis can be extended to organize health monitoring system for specially elderly persons. PMID:25110724

Shin, Seungsoo

2014-01-01

296

Fractional Langevin model of gait variability.  

PubMed

The stride interval in healthy human gait fluctuates from step to step in a random manner and scaling of the interstride interval time series motivated previous investigators to conclude that this time series is fractal. Early studies suggested that gait is a monofractal process, but more recent work indicates the time series is weakly multifractal. Herein we present additional evidence for the weakly multifractal nature of gait. We use the stride interval time series obtained from ten healthy adults walking at a normal relaxed pace for approximately fifteen minutes each as our data set. A fractional Langevin equation is constructed to model the underlying motor control system in which the order of the fractional derivative is itself a stochastic quantity. Using this model we find the fractal dimension for each of the ten data sets to be in agreement with earlier analyses. However, with the present model we are able to draw additional conclusions regarding the nature of the control system guiding walking. The analysis presented herein suggests that the observed scaling in interstride interval data may not be due to long-term memory alone, but may, in fact, be due partly to the statistics. PMID:16076394

West, Bruce J; Latka, Miroslaw

2005-01-01

297

Evaluating alternative gait strategies using evolutionary robotics  

PubMed Central

Evolutionary robotics is a branch of artificial intelligence concerned with the automatic generation of autonomous robots. Usually the form of the robot is predefined and various computational techniques are used to control the machine's behaviour. One aspect is the spontaneous generation of walking in legged robots and this can be used to investigate the mechanical requirements for efficient walking in bipeds. This paper demonstrates a bipedal simulator that spontaneously generates walking and running gaits. The model can be customized to represent a range of hominoid morphologies and used to predict performance parameters such as preferred speed and metabolic energy cost. Because it does not require any motion capture data it is particularly suitable for investigating locomotion in fossil animals. The predictions for modern humans are highly accurate in terms of energy cost for a given speed and thus the values predicted for other bipeds are likely to be good estimates. To illustrate this the cost of transport is calculated for Australopithecus afarensis. The model allows the degree of maximum extension at the knee to be varied causing the model to adopt walking gaits varying from chimpanzee-like to human-like. The energy costs associated with these gait choices can thus be calculated and this information used to evaluate possible locomotor strategies in early hominids. PMID:15198699

Sellers, William I; Dennis, Louise A; Wang, W -J; Crompton, Robin H

2004-01-01

298

Gait correlation analysis based human identification.  

PubMed

Human gait identification aims to identify people by a sequence of walking images. Comparing with fingerprint or iris based identification, the most important advantage of gait identification is that it can be done at a distance. In this paper, silhouette correlation analysis based human identification approach is proposed. By background subtracting algorithm, the moving silhouette figure can be extracted from the walking images sequence. Every pixel in the silhouette has three dimensions: horizontal axis (x), vertical axis (y), and temporal axis (t). By moving every pixel in the silhouette image along these three dimensions, we can get a new silhouette. The correlation result between the original silhouette and the new one can be used as the raw feature of human gait. Discrete Fourier transform is used to extract features from this correlation result. Then, these features are normalized to minimize the affection of noise. Primary component analysis method is used to reduce the features' dimensions. Experiment based on CASIA database shows that this method has an encouraging recognition performance. PMID:24592144

Chen, Jinyan

2014-01-01

299

Introduction to ball bearings  

NASA Technical Reports Server (NTRS)

The purpose of a ball bearing is to provide a relative positioning and rotational freedom while transmitting a load between two structures, usually a shaft and a housing. For high rotational speeds (e.g., in gyroscope ball bearings) the purpose can be expanded to include rotational freedom with practically no wear in the bearing. This condition can be achieved by separating the bearing parts with a coherent film of fluid known as an elastohydrodynamic film. This film can be maintained not only when the bearing carries the load on a shaft, but also when the bearing is preloaded to position the shaft to within micro- or nano-inch accuracy and stability. Background information on ball bearings is provided, different types of ball bearings and their geometry and kinematics are defined, bearing materials, manufacturing processes, and separators are discussed. It is assumed, for the purposes of analysis, that the bearing carries no load.

Hamrock, B. J.; Dowson, D.

1981-01-01

300

Wavelet spectrum analysis for bearing fault diagnostics  

NASA Astrophysics Data System (ADS)

A new signal processing technique, wavelet spectrum analysis, is proposed in this paper for incipient bearing fault diagnostics. This technique starts from investigating the resonance signatures over selected frequency bands to extract the representative features. A novel strategy is suggested for the deployment of the wavelet centre frequencies. A weighted Shannon function is proposed to synthesize the wavelet coefficient functions to enhance feature characteristics, whereas the applied weights are from a statistical index that quantifies the effect of different wavelet centre frequencies on feature extraction. An averaged autocorrelation spectrum is adopted to highlight the feature characteristics related to bearing health conditions. The performance of this proposed technique is examined by a series of experimental tests corresponding to different bearing conditions. Test results show that this new signal processing technique is an effective bearing fault detection method, which is especially useful for non-stationary feature extraction and analysis.

Liu, Jie; Wang, Wilson; Golnaraghi, Farid; Liu, Kefu

2008-01-01

301

Gait asymmetry in patients with Parkinson’s disease and elderly fallers: when does the bilateral coordination of gait require attention?  

Microsoft Academic Search

While it is known that certain pathologies may impact on left–right symmetry of gait, little is known about the mechanisms\\u000a that contribute to gait symmetry or how high in the hierarchy of the control of gait symmetry is regulated in humans. To assess\\u000a the contribution of cognitive function to gait symmetry, we measured gait asymmetry (GA) in three subject groups,

Galit Yogev; Meir Plotnik; Chava Peretz; Nir Giladi; Jeffrey M. Hausdorff

2007-01-01

302

Bearing Failure Detection  

NASA Technical Reports Server (NTRS)

Shaker Research Corporation, under a contract with NASA, produced a test vehicle that measures resonant frequency of railroad roller bearings to identify source of bearings defects. Marshall scientists have developed a detection concept based on fact that bearing defects themselves excite resonant frequency of rolling elements of bearing as they impact the defect. By detecting resonant frequency and subsequently analyzing character of the signal, bearing defects may be detected and identified as to source. The bearing fault detector will help eliminate this cause of derailments.

1976-01-01

303

Factors Related to Gait Function in Post-stroke Patients.  

PubMed

[Purpose] Gait function after a stroke is an important factor for determining a patient's ability to independently perform activities of daily living (ADL). The objective of this study was to elucidate the factors associated with gait function in post-stroke patients. [Subjects] Thirty-nine stroke patients (16 females and 23 males; average age 67.82 ± 10.96?years; post-onset duration: 200.18 ± 27.14 days) participated in this study. [Methods] Their gait function, motor function (Manual Muscle Test [MMT] and Brünnstrom stage), level of cognition (Mini-Mental State Examination score [MMSE], and the Loewenstein Occupational Therapy Cognitive Assessment for the Geriatric Population [LOTCA-G]), and ADL (Korean modified Barthel index [K-MBI]) were assessed. [Results] The degree of gait function showed significant positive correlations with the following variables: MMT of the elbow, knee, ankle and wrist; Brünnstrom stage; MMSE; LOTCA-G subscores except motor praxis; K-MBI. Stepwise linear regression analysis revealed the Brünnstrom stage was the only explanatory variable closely associated with gait level. [Conclusion] Gait function of post-stroke patients was related to motor function, cognition, and ADL. In particular, there is a significant association between gait level and the Brünnstrom stages, reflecting the importance of monitoring the motor recovery of gait function in post-stroke patients. PMID:25540503

Cho, Ki Hun; Lee, Joo Young; Lee, Kun Jae; Kang, Eun Kyoung

2014-12-01

304

Dynamic knee loads during gait predict proximal tibial bone distribution  

Microsoft Academic Search

This study tested the validity of the prediction of dynamic knee loads based on gait measurements. The relationship between the predicted loads at the knee and the distribution of bone between the medial and lateral sides of the tibia was examined. The motion and external forces and moments at the knee were measured during gait and a statically determinate muscle

Debra E. Hurwitz; Dale R. Sumner; Thomas P. Andriacchi; David A. Sugar

1998-01-01

305

Biped model for determining selected performance resource requirements during gait  

Microsoft Academic Search

A description is given of the development of a dynamic biped model for use in determining the amount of performance resources required to perform a predetermined gait task. The gait task is specified by identifying the desired cadence and stride length, and the performance resources predicted by the model are the joint torques, displacements, and velocities associated with the hip,

James J. Carollo; George V. Kondraske

1988-01-01

306

Emotional State Affects the Initiation of Forward Gait  

Microsoft Academic Search

The aim of the current study was to determine the extent to which pleasant and unpleasant emotional states impact the initiation of forward gait. Participants initiated gait and walked for several steps following the presentation of low arousing pleasant, high arousing pleasant, low arousing unpleasant, high arousing unpleasant, and neutral pictures. Reaction time, displacement, and velocity of the center of

Kelly M. Naugle; Chris J. Hass; Jessica Joyner; Stephen A. Coombes; Christopher M. Janelle

2011-01-01

307

Managing variability in the summary and comparison of gait data  

Microsoft Academic Search

Variability in quantitative gait data arises from many potential sources, including natural temporal dynamics of neuromotor control, pathologies of the neurological or musculoskeletal systems, the effects of aging, as well as variations in the external environment, assistive devices, instrumentation or data collection methodologies. In light of this variability, unidimensional, cycle-based gait variables such as stride period should be viewed as

Tom Chau; Scott Young; Sue Redekop

2005-01-01

308

Gait and electromyographic analysis of anterior cruciate ligament deficient subjects  

Microsoft Academic Search

Some anterior cruciate ligament deficient (ACLD) patients can overcome passive sagittal joint laxity and maintain dynamic stability of the knee joint. Gait analysis with electromyographic (EMG) support was used in an attempt to identify mechanisms whereby ACLD individuals achieve this functional stability. A group of 18 patients with arthroscopically proven, unilateral, chronic (>6 months) ACLD had their gait assessed using

D. J. Beard; R. S. Soundarapandian; J. J. O'Connor; C. A. F. Dodd

1996-01-01

309

DRAG: a database for recognition and analasys of gait  

NASA Astrophysics Data System (ADS)

A novel approach is proposed for creating a standardized and comprehensive database for gait analysis. The field of gait analysis is gaining increasing attention for applications such as visual surveillance, human-computer interfaces, and gait recognition and rehabilitation. Numerous algorithms have been developed for analyzing and processing gait data; however, a standard database for their systematic evaluation does not exist. Instead, existing gait databases consist of subsets of kinematic, kinetic, and electromyographic activity recordings by different investigators, at separate laboratories, and under varying conditions. Thus, the existing databases are neither homogenous nor sufficiently populated to statistically validate the algorithms. In this paper, a methodology for creating a database is presented, which can be used as a common ground to test the performance of algorithms that rely upon external marker data, ground reaction loading data, and/or video images. The database consists of: (1) synchronized motion-capture data (3D marker data) obtained using external markers, (2) computed joint angles, and (3) ground reaction loading acquired with plantar pressure insoles. This database could be easily expanded to include synchronized video, which will facilitate further development of video-based algorithms for motion tracking. This eventually could lead to the realization of markerless gait tracking. Such a system would have extensive applications in gait recognition, as well as gait rehabilitation. The entire database (marker, angle, and force data) will be placed in the public domain, and made available for downloads over the World Wide Web.

Kuchi, Prem; Hiremagalur, Raghu Ram V.; Huang, Helen; Carhart, Michael; He, Jiping; Panchanathan, Sethuraman

2003-11-01

310

Hip contact forces and gait patterns from routine activities  

Microsoft Academic Search

In vivo loads acting at the hip joint have so far only been measured in few patients and without detailed documentation of gait data. Such information is required to test and improve wear, strength and fixation stability of hip implants. Measurements of hip contact forces with instrumented implants and synchronous analyses of gait patterns and ground reaction forces were performed

G Bergmann; G Deuretzbacher; M Heller; F Graichen; A Rohlmann; J Strauss; G. N Duda

2001-01-01

311

Research Review Falls and Freezing of Gait in Parkinson's Disease  

E-print Network

Society Key words: Parkinson's disease; falls; gait; freezing; patho- physiology; treatment In recentResearch Review Falls and Freezing of Gait in Parkinson's Disease: A Review of Two Interconnected that are common in Parkinson's disease. Both symp- toms are often incapacitating for affected patients

312

Conversive gait disorder: you cannot miss this diagnosis.  

PubMed

Bizarre, purposeless movements and inconsistent findings are typical of conversive gaits. The objective of the present paper is to review some phenomenological aspects of twenty-five consecutive conversive gait disorder patients. Some variants are typical - knees give way-and-recover presentation, monoparetic, tremulous, and slow motion - allowing clinical diagnosis with high precision. PMID:24863514

Maranhão-Filho, Péricles; Silva, Carlos Eduardo da Rocha E; Vincent, Maurice Borges

2014-05-01

313

Silhouette Analysis-Based Gait Recognition for Human Identification  

Microsoft Academic Search

Human identification at a distance has recently gained growing interest from computer vision researchers. Gait recognition aims essentially to address this problem by identifying people based on the way they walk. In this paper, a simple but efficient gait recognition algorithm using spatial-temporal silhouette analysis is proposed. For each image sequence, a background subtraction algorithm and a simple correspondence procedure

Liang Wang; Tieniu Tan; Huazhong Ning; Weiming Hu

2003-01-01

314

Simplest Representation Yet for Gait Recognition: Averaged Silhouette  

Microsoft Academic Search

We present a robust representation for gait recogni- tion that is compact, easy to construct, and affords effi- cient matching. Instead of a time series based represen- tation comprising of a sequence of raw silhouette frames or of features extracted therein, as has been the prac- tice, we simply align and average the silhouettes over one gait cycle. We then

Zongyi Liu; Sudeep Sarkar

2004-01-01

315

Silhouette-Based Human Identification from Body Shape and Gait  

Microsoft Academic Search

Our goal is to establish a simple baseline method for human identification based on body shape and gait. This baseline recognition method provides a lower bound against which to evaluate more complicated procedures. We present a viewpoint dependent technique based on template match- ing of body silhouettes. Cyclic gait analysis is performed to extract key frames from a test sequence.

Robert T. Collins; Ralph Gross; Jianbo Shi

2002-01-01

316

Automated recognition of human gait pattern using manifold learning algorithm  

Microsoft Academic Search

In this paper, we investigated the application of the manifold learning algorithm in gait data analysis for the improvement of the gait classification performance. A manifold learning algorithm such as isometric feature mapping algorithm (ISOMAP) was firstly employed to perform nonlinear feature extraction for initiating the training set, and its effect on a subsequent classification was then tested in combination

Jianning Wu

2012-01-01

317

Gait mechanics in chronic ACL deficiency and subsequent repair  

Microsoft Academic Search

Objective. To determine how normal gait patterns may change as a result of chronic anterior cruciate ligament deficiency and subsequent reconstructive surgery.Design. Gait testing of 10 chronic anterior cruciate ligament deficient subjects prior to and 3 months following reconstructive surgery, and 10 uninjured controls.Background. There is controversy whether persons with chronic anterior cruciate ligament deficiency develop a “quadriceps avoidance” pattern

Reed Ferber; Louis R. Osternig; Marjorie H. Woollacott; Noah J. Wasielewski; Ji-Hang Lee

2002-01-01

318

Biomechanical analysis of gait adaptation in the nematode Caenorhabditis elegans.  

PubMed

To navigate different environments, an animal must be able to adapt its locomotory gait to its physical surroundings. The nematode Caenorhabditis elegans, between swimming in water and crawling on surfaces, adapts its locomotory gait to surroundings that impose approximately 10,000-fold differences in mechanical resistance. Here we investigate this feat by studying the undulatory movements of C. elegans in Newtonian fluids spanning nearly five orders of magnitude in viscosity. In these fluids, the worm undulatory gait varies continuously with changes in external load: As load increases, both wavelength and frequency of undulation decrease. We also quantify the internal viscoelastic properties of the worm's body and their role in locomotory dynamics. We incorporate muscle activity, internal load, and external load into a biomechanical model of locomotion and show that (i) muscle power is nearly constant across changes in locomotory gait, and (ii) the onset of gait adaptation occurs as external load becomes comparable to internal load. During the swimming gait, which is evoked by small external loads, muscle power is primarily devoted to bending the worm's elastic body. During the crawling gait, evoked by large external loads, comparable muscle power is used to drive the external load and the elastic body. Our results suggest that C. elegans locomotory gait continuously adapts to external mechanical load in order to maintain propulsive thrust. PMID:21048086

Fang-Yen, Christopher; Wyart, Matthieu; Xie, Julie; Kawai, Risa; Kodger, Tom; Chen, Sway; Wen, Quan; Samuel, Aravinthan D T

2010-11-23

319

Factors Related to Gait Function in Post-stroke Patients  

PubMed Central

[Purpose] Gait function after a stroke is an important factor for determining a patient’s ability to independently perform activities of daily living (ADL). The objective of this study was to elucidate the factors associated with gait function in post-stroke patients. [Subjects] Thirty-nine stroke patients (16 females and 23 males; average age 67.82 ± 10.96?years; post-onset duration: 200.18 ± 27.14 days) participated in this study. [Methods] Their gait function, motor function (Manual Muscle Test [MMT] and Brünnstrom stage), level of cognition (Mini-Mental State Examination score [MMSE], and the Loewenstein Occupational Therapy Cognitive Assessment for the Geriatric Population [LOTCA-G]), and ADL (Korean modified Barthel index [K-MBI]) were assessed. [Results] The degree of gait function showed significant positive correlations with the following variables: MMT of the elbow, knee, ankle and wrist; Brünnstrom stage; MMSE; LOTCA-G subscores except motor praxis; K-MBI. Stepwise linear regression analysis revealed the Brünnstrom stage was the only explanatory variable closely associated with gait level. [Conclusion] Gait function of post-stroke patients was related to motor function, cognition, and ADL. In particular, there is a significant association between gait level and the Brünnstrom stages, reflecting the importance of monitoring the motor recovery of gait function in post-stroke patients.

Cho, Ki Hun; Lee, Joo Young; Lee, Kun Jae; Kang, Eun Kyoung

2014-01-01

320

Optimal energy gait planning for humanoid robot using geodesics  

Microsoft Academic Search

A novel gait planning method using geodesics for humanoid robot is given in this paper. Both center of gravity (COG) and the exact Single Support Phase (SSP) are studied in our energy optimal gait planning based on geodesics. The kinetic energy of a 2-dimensional inverted pendulum is obtained at first. We regard the kinetic energy as the Riemannian metric and

Liandong Zhang; Changjiu Zhou; Peijie Zhang; Zhiwei Song; Yue Pik Kong; Xinyu Han

2010-01-01

321

Dynamic markers of altered gait rhythm in amyotrophic lateral sclerosis  

E-print Network

Dynamic markers of altered gait rhythm in amyotrophic lateral sclerosis JEFFREY M. HAUSDORFF,1 of altered gait rhythm in amyotrophic lateral sclerosis. J Appl Physiol 88: 2045­ 2053, 2000.--Amyotrophic dynamics AMYOTROPHIC LATERAL SCLEROSIS (ALS) is a disorder primarily affecting the motoneurons

322

Genetic programming based automatic gait generation for quadruped robots  

Microsoft Academic Search

This paper introduces a new approach to develop a fast gait for quadruped robot using genetic programming (GP). Several recent approaches have focused on the genetic algorithm (GA) to generate a gait automatically and shown significant improvements over previous results. Most of current GA based approaches use pre-selected parameters, but it is difficult to select the appropriate parameters for the

Kisung Seo; Soohwan Hyun

2008-01-01

323

Quantitative gait measurement with pulse-Doppler radar for passive in-home gait assessment.  

PubMed

In this paper, we propose a pulse-Doppler radar system for in-home gait assessment of older adults. A methodology has been developed to extract gait parameters including walking speed and step time using Doppler radar. The gait parameters have been validated with a Vicon motion capture system in the lab with 13 participants and 158 test runs. The study revealed that for an optimal step recognition and walking speed estimation, a dual radar set up with one radar placed at foot level and the other at torso level is necessary. An excellent absolute agreement with intraclass correlation coefficients of 0.97 was found for step time estimation with the foot level radar. For walking speed, although both radars show excellent consistency they all have a system offset compared to the ground truth due to walking direction with respect to the radar beam. The torso level radar has a better performance (9% offset on average) in the speed estimation compared to the foot level radar (13%-18% offset). Quantitative analysis has been performed to compute the angles causing the systematic error. These lab results demonstrate the capability of the system to be used as a daily gait assessment tool in home environments, useful for fall risk assessment and other health care applications. The system is currently being tested in an unstructured home environment. PMID:24771566

Wang, Fang; Skubic, Marjorie; Rantz, Marilyn; Cuddihy, Paul E

2014-09-01

324

Quantitative Gait Measurement With Pulse-Doppler Radar for Passive In-Home Gait Assessment  

PubMed Central

In this paper, we propose a pulse-Doppler radar system for in-home gait assessment of older adults. A methodology has been developed to extract gait parameters including walking speed and step time using Doppler radar. The gait parameters have been validated with a Vicon motion capture system in the lab with 13 participants and 158 test runs. The study revealed that for an optimal step recognition and walking speed estimation, a dual radar set up with one radar placed at foot level and the other at torso level is necessary. An excellent absolute agreement with intraclass correlation coefficients of 0.97 was found for step time estimation with the foot level radar. For walking speed, although both radars show excellent consistency they all have a system offset compared to the ground truth due to walking direction with respect to the radar beam. The torso level radar has a better performance (9% offset on average) in the speed estimation compared to the foot level radar (13%–18% offset). Quantitative analysis has been performed to compute the angles causing the systematic error. These lab results demonstrate the capability of the system to be used as a daily gait assessment tool in home environments, useful for fall risk assessment and other health care applications. The system is currently being tested in an unstructured home environment. PMID:24771566

Skubic, Marjorie; Rantz, Marilyn; Cuddihy, Paul E.

2014-01-01

325

Gait pathology assessed with Gillette Gait Index in patients after CNS tumour treatment  

Microsoft Academic Search

Brain tumour is the third leading cause of death in children and adolescents younger than 16 years of age. The increasing survival rate of these patients makes their follow-up and quality of life assessment an important task. This study evaluated the gait pathology of the patients after the combined treatment for central nervous system (CNS) tumours. It assessed if the

Ma?gorzata Syczewska; Bo?ena Dembowska-Bagi?ska; Marta Perek-Polnik; Ma?gorzata Kalinowska; Danuta Perek

2010-01-01

326

Optimality Principles for Model-Based Prediction of Human Gait  

PubMed Central

Although humans have a large repertoire of potential movements, gait patterns tend to be stereotypical and appear to be selected according to optimality principles such as minimal energy. When applied to dynamic musculoskeletal models such optimality principles might be used to predict how a patient’s gait adapts to mechanical interventions such as prosthetic devices or surgery. In this paper we study the effects of different performance criteria on predicted gait patterns using a 2D musculoskeletal model. The associated optimal control problem for a family of different cost functions was solved utilizing the direct collocation method. It was found that fatigue-like cost functions produced realistic gait, with stance phase knee flexion, as opposed to energy-related cost functions which avoided knee flexion during the stance phase. We conclude that fatigue minimization may be one of the primary optimality principles governing human gait. PMID:20074736

Ackermann, Marko; van den Bogert, Antonie J.

2010-01-01

327

Joint kinetics during Tai Chi gait and normal walking gait in young and elderly Tai Chi Chuan practitioners  

Microsoft Academic Search

BackgroundTai Chi Chuan is becoming a popular exercise among elders. This study measured the inter-segmental forces and moments at the lower extremity joints during a Tai Chi gait as compared to those during normal walking gait, in both apparently healthy young and elderly Tai Chi Chuan practitioners.

Ge Wu; Debra Millon

2008-01-01

328

Gait and cognition: The relationship between gait stability and variability with executive function in persons with and without dementia  

Microsoft Academic Search

Besides cognitive decline, dementia is characterized by gait changes and increased fall risk, also in early stages of the disease. The aim of this study was to investigate differences in the relationship between executive function and gait variability and stability during single task and dual task walking in persons with and without dementia. The study sample consisted of three groups:

Trienke IJmker; Claudine J. C. Lamoth

329

Experiments with needle bearings  

NASA Technical Reports Server (NTRS)

Experiments and results are presented in testing needle bearings, especially in comparison with roller bearings. Reduction in coefficient of friction is discussed as well as experimental methods and recording devices.

Ferretti, Pericle

1933-01-01

330

Tracking Polar Bears  

NSDL National Science Digital Library

In this interactive activity adapted from the USGS Alaska Science Center, track the movements of a polar bear as it migrates across the changing Arctic sea ice and compare the paths of four different polar bears.

Foundation, Wgbh E.

2008-01-17

331

Mechanical spin bearings  

NASA Technical Reports Server (NTRS)

A spin bearing assembly including, a pair of mutually opposing complementary bearing support members having mutually spaced apart bearing support surfaces which may be, for example, bearing races and a set of spin bearings located therebetween. Each spin bearing includes a pair of end faces, a central rotational axis passing through the end faces, a waist region substantially mid-way between the end faces and having a first thickness dimension, and discrete side surface regions located between the waist region and the end faces and having a second thickness dimension different from the first thickness dimension of the waist region and wherein the side surface regions further have respective curvilinear contact surfaces adapted to provide a plurality of bearing contact points on the bearing support members.

Vranish, John M. (Inventor)

1998-01-01

332

Probabilistic Gait Classification in Children with Cerebral Palsy: A Bayesian Approach  

ERIC Educational Resources Information Center

Three-dimensional gait analysis (3DGA) generates a wealth of highly variable data. Gait classifications help to reduce, simplify and interpret this vast amount of 3DGA data and thereby assist and facilitate clinical decision making in the treatment of CP. CP gait is often a mix of several clinically accepted distinct gait patterns. Therefore,…

Van Gestel, Leen; De Laet, Tinne; Di Lello, Enrico; Bruyninckx, Herman; Molenaers, Guy; Van Campenhout, Anja; Aertbelien, Erwin; Schwartz, Mike; Wambacq, Hans; De Cock, Paul; Desloovere, Kaat

2011-01-01

333

Gait Patterns in Hemiplegic Children with Cerebral Palsy: Comparison of Right and Left Hemiplegia  

ERIC Educational Resources Information Center

The aims of this study are to compare quantitatively the gait strategy of the right and left hemiplegic children with Cerebral Palsy (CP) using gait analysis. The gait strategy of 28 right hemiparetic CP (RHG) and 23 left hemiparetic CP (LHG) was compared using gait analysis (spatio-temporal and kinematic parameters) and considering the hemiplegic…

Galli, Manuela; Cimolin, Veronica; Rigoldi, Chiara; Tenore, Nunzio; Albertini, Giorgio

2010-01-01

334

Comparative analysis of the gait disorder of normal pressure hydrocephalus and Parkinson's disease  

Microsoft Academic Search

OBJECTIVESComparative gait analyses in neurological diseases interfering with locomotion are of particular interest, as many hypokinetic gait disorders have the same main features. The aim of the present study was (1) to compare the gait disturbance in normal pressure hydrocephalus and Parkinson's disease; (2) to evaluate which variables of the disturbed gait pattern respond to specific treatment in both diseases;

H Stolze; J P Kuhtz-Buschbeck; H Drücke; K Jöhnk; M Illert; G Deuschl

2001-01-01

335

A Gait Monitoring System Based on Air Pressure Sensors Embedded in a Shoe  

Microsoft Academic Search

Measurement of ground contact forces (GCFs) provides necessary information to detect human gait phases. In this paper, a new analysis method of the GCF signals is discussed for detection of the gait phases. Human gaits are complicated, and the gait phases cannot be exactly distinguished by comparing sensor outputs to a threshold. This paper proposes a method by fuzzy logic

Kyoungchul Kong; Masayoshi Tomizuka

2009-01-01

336

Smooth and continuous human gait phase detection based on foot pressure patterns  

Microsoft Academic Search

Measurement of ground contact forces (GCF) provides necessary information to detect human gait phases. In this paper, a new analysis method of the GCF signals is discussed for detection of the gait phases. Human gaits are complicated, and the gait phases can not be exactly distinguished by comparing sensor outputs to a threshold. This paper mainly discusses how to detect

Kyoungchul Kong; Masayoshi Tomizuka

2008-01-01

337

A comparison of neural networks and support vector machines for recognizing young-old gait patterns  

Microsoft Academic Search

The aim of this paper is to apply artificial intelligence techniques (neural networks (NN), and support vector machines (SVM)) for the automatic identification of young-old gait types from their respective gait measures. The ability of such discrimination has many advantages including, early identification of at-risk gait for falls prevention in the older population. The gaits of 12 young and 12

R. Begg; J. Kamruzzaman

2003-01-01

338

The initiation of gait in young, elderly, and Parkinson's disease subjects  

Microsoft Academic Search

Gait initiation is a transient movement between upright posture and steady-state gait. Kinematic, kinetic and electromyographic data have been documented in healthy young subjects. However, there is little published data on the elderly and on Parkinson's disease (PD) subjects who are known to `freeze' when initiating gait. It was the purpose of this project to measure gait initiation in young,

Suzanne E Halliday; David A Winter; James S Frank; Aftab E Patla; François Prince

1998-01-01

339

Intra-subject stride-to-stride variability: Selecting subject's representative gait pattern  

Microsoft Academic Search

Stride-to-stride variability is well known and important phenomenon often used for estimation of the gait fluctuations and indicative measure for potential risk of falling in elderly. In many gait analysis studies and the descriptions of new processing and analysis methods, the problem of selecting representative gait cycle is solved with choosing one gait cycle from the middle of the recording

Milica Djuric-Jovicic; Vera Miler-Jerkovic

2011-01-01

340

A new classification of higher level gait disorders in patients with cerebral multi-infarct states  

Microsoft Academic Search

Background: cerebral multi-infarct states may lead to gait disorders in the absence of cognitive impairment. Where these gait disorders occur in the absence of neurological signs they have been termed gait apraxia or more recently higher-level gait disorders. In this paper we hypothesise three main types based on presumptive sites of anatomical damage: (a) Ignition Apraxia, where damage is predominantly

RICHARD LISTON; J ANE MICKELBOROUGH; J ACQUELINE BENE; R AYMOND TALLIS

2003-01-01

341

Timed Gait Test: Normative Data for the Assessment of the AIDS Dementia Complex  

Microsoft Academic Search

The Timed Gait test is a standardized procedure assessing motor dysfunction of lower extremities and gait abnormalities associated with AIDS dementia complex. Heretofore, interpretations of Timed Gait results have been hampered by the lack of normative data. We provide results on this test derived from 1,549 subjects (HIV?seronegatives (HIV?) and seropositives (HIV+) classified according to ADC stage). Timed Gait was

Kevin R. Robertson; Thomas D. Parsons; John J. Sidtis; Tina Hanlon Inman; Wendy T. Robertson; Colin D. Hall; Richard W. Price

2006-01-01

342

Gait Patterns in Twins with Cerebral Palsy: Similarities and Development over Time after Multilevel Surgery  

ERIC Educational Resources Information Center

To examine gait patterns and gait quality, 7 twins with cerebral palsy were measured preoperatively and after surgical intervention. The aim was to study differences and/or similarities in gait between twins, the influence of personal characteristics and birth conditions, and to describe the development of gait over time after single event…

van Drongelen, Stefan; Dreher, Thomas; Heitzmann, Daniel W. W.; Wolf, Sebastian I.

2013-01-01

343

How much muscle strength is required to walk in a crouch gait?  

PubMed Central

Muscle weakness is commonly cited as a cause of crouch gait in individuals with cerebral palsy; however, outcomes after strength training are variable and mechanisms by which muscle weakness may contribute to crouch gait are unclear. Understanding how much muscle strength is required to walk in a crouch gait compared to an unimpaired gait may provide insight into how muscle weakness contributes to crouch gait and assist in the design of strength training programs. The goal of this study was to examine how much muscle groups could be weakened before crouch gait becomes impossible. To investigate this question, we first created muscle-driven simulations of gait for three typically-developing children and six children with cerebral palsy who walked with varying degrees of crouch severity. We then simulated muscle weakness by systematically reducing the maximum isometric force of each muscle group until the simulation could no longer reproduce each subject’s gait. This analysis indicated that moderate crouch gait required significantly more knee extensor strength than unimpaired gait. In contrast, moderate crouch gait required significantly less hip abductor strength than unimpaired gait, and mild crouch gait required significantly less ankle plantarflexor strength than unimpaired gait. The reduced strength required from the hip abductors and ankle plantarflexors during crouch gait suggests that weakness of these muscle groups may contribute to crouch gait and that these muscle groups are potential targets for strength training. PMID:22959837

Steele, Katherine M.; van der Krogt, Marjolein M.; Schwartz, Michael H.; Delp, Scott L.

2012-01-01

344

Dual Gait Generative Models for Human Motion Estimation From a Single Camera  

Microsoft Academic Search

This paper presents a general gait representation framework for video-based human motion estimation. Specifically, we want to estimate the kinematics of an unknown gait from image sequences taken by a single camera. This approach involves two generative models, called the kinematic gait generative model (KGGM) and the visual gait generative model (VGGM), which represent the kinematics and appearances of a

Xin Zhang; Guoliang Fan

2010-01-01

345

Polar Bears Change Diet  

NSDL National Science Digital Library

This radio broadcast from 2001 explains how polar bears have adjusted their diet due to the climate warming around Hudson Bay, Canada. The ringed seals that polar bears normally eat have been harder for polar bears to get to, due to disappearing ice. This has forced polar bears to begin eating harbor seals and bearded seals. The clip is 4 minutes and 15 seconds in length.

Schneider, Doug

2007-12-12

346

Tracking Polar Bears  

USGS Multimedia Gallery

Movements of 9 satellite-collared adult female polar bears were tracked in February, 2010 by satellite telemetry. Bears were collared in 2007, 2008, and 2009 on the spring-time sea ice of the southern Beaufort Sea or on the autumn pack ice in 2009. Polar bear satellite telemetry data are shown with ...

2010-04-13

347

Good bearings reduce downtime  

Microsoft Academic Search

Points out that a poorly maintained $100 bearing can hold up the operation of a $1-million conveyor. Of all the moving parts in a coal conveyor system, few cost less or last longer than anti-friction bearings. Most modern conveyor systems are equipped with 2 types of bearings: troughing idlers, spaced at regular intervals to support the conveyor belt as it

J. Kinney; J. Foster

1982-01-01

348

Grizzly bears and forestry  

Microsoft Academic Search

Today's growing demand for timber is increasing road development in once roadless forest ecosystems. Roads create both local changes in plant communities and landscape-level changes in forest connectivity. Roads also increase human access, which can be detrimental to species such as grizzly bears. Because most grizzly bear mortalities occur near roads, we examined grizzly bear attractants near roads, which could

C. L. Roever; M. S. Boyce; G. B. Stenhouse

2008-01-01

349

1-Way Bearing  

NASA Technical Reports Server (NTRS)

A one-way bearing is provided having sprags and rolling bearings both disposed between an inner and an outer race. The sprags may comprise three-dimensional sprags for preventing rotation in a non-preferential direction. The roll- ing bearings may comprise thrust rollers for transmitting axial, tilt, and radial loads between the inner and outer races.

Vranish, John M. (Inventor)

2003-01-01

350

Supertough Stainless Bearing Steel  

NASA Technical Reports Server (NTRS)

Composition and processing of supertough stainless bearing steel designed with help of computer-aided thermodynamic modeling. Fracture toughness and hardness of steel exceeds those of other bearing steels like 440C stainless bearing steel. Developed for service in fuel and oxidizer turbopumps on Space Shuttle main engine. Because of strength and toughness, also proves useful in other applications like gears and surgical knives.

Olson, Gregory B.

1995-01-01

351

Cryogenic Hybrid Magnetic Bearing  

NASA Technical Reports Server (NTRS)

Cryogenic hybrid magnetic bearing is example of class of magnetic bearings in which permanent magnets and electromagnets used to suspend shafts. Electromagnets provide active control of position of shaft. Bearing operates at temperatures from -320 degrees F (-196 degrees C) to 650 degrees F (343 degrees C); designed for possible use in rocket-engine turbopumps, where effects of cryogenic environment and fluid severely limit lubrication of conventional ball bearings. This and similar bearings also suitable for terrestrial rotating machinery; for example, gas-turbine engines, high-vacuum pumps, canned pumps, precise gimbals that suspend sensors, and pumps that handle corrosive or gritty fluids.

Meeks, Crawford R.; Dirusso, Eliseo; Brown, Gerald V.

1994-01-01

352

Video-Based Human Motion Estimation by Part-Whole Gait Manifold Learning  

Microsoft Academic Search

\\u000a This chapter presents a general gait representation framework for video-based human motion estimation that involves gait modeling\\u000a at both the whole and part levels. Our goal is to estimate the kinematics of an unknown gait from image sequences taken by\\u000a a single camera. This approach involves two generative models, called the kinematic gait generative model (KGGM) and the visual\\u000a gait

Guoliang Fan; Xin Zhang

353

Cholinergic dysfunction contributes to gait disturbance in early Parkinson's disease.  

PubMed

Gait disturbance is an early feature in Parkinson's disease. Its pathophysiology is poorly understood; however, cholinergic dysfunction may be a non-dopaminergic contributor to gait. Short-latency afferent inhibition is a surrogate measure of cholinergic activity, allowing the contribution of cholinergic dysfunction to gait to be evaluated. We hypothesized that short-latency afferent inhibition would be an independent predictor of gait dysfunction in early Parkinson's disease. Twenty-two participants with Parkinson's disease and 22 age-matched control subjects took part in the study. Gait was measured objectively using an instrumented walkway (GAITRite), and subjects were asked to walk at their preferred speed for 2 min around a 25-m circuit. Spatiotemporal characteristics (speed, stride length, stride time and step width) and gait dynamics (variability described as the within subject standard deviation of: speed, stride time, stride length and step width) were determined. Short-latency afferent inhibition was measured by conditioning motor evoked potentials, elicited by transcranial magnetic stimulation of the motor cortex, with electrical stimuli delivered to the contralateral median nerve at intervals ranging from N20 (predetermined) to N20 + 4 ms. Short-latency afferent inhibition was determined as the percentage difference between test and conditioned response for all intervals and was described as the group mean. Participants were optimally medicated at the time of testing. Participants with Parkinson's disease had significantly reduced gait speed (P = 0.002), stride length (P = 0.008) and stride time standard deviation (P = 0.001). Short-latency afferent inhibition was also significantly reduced in participants with Parkinson's disease (P = 0.004). In participants with Parkinson's disease, but not control subjects, significant associations were found between gait speed, short-latency afferent inhibition, age and postural instability and gait disorder score (Movement Disorders Society Unified Parkinson's Disease Rating Scale) and attention, whereas global cognition and depression were marginally significant. No other gait variables were associated with short-latency afferent inhibition. A multiple hierarchical regression model explored the contribution of short-latency afferent inhibition to gait speed, controlling for age, posture and gait symptoms (Postural Instability and Gait Disorder score-Movement Disorders Society Unified Parkinson's Disease Rating Scale), attention and depression. Regression analysis in participants with Parkinson's disease showed that reduced short-latency afferent inhibition was an independent predictor of slower gait speed, explaining 37% of variability. The final model explained 72% of variability in gait speed with only short-latency afferent inhibition and attention emerging as independent determinants. The results suggest that cholinergic dysfunction may be an important and early contributor to gait dysfunction in Parkinson's disease. The findings also point to the contribution of non-motor mechanisms to gait dysfunction. Our study provides new insights into underlying mechanisms of non-dopaminergic gait dysfunction, and may help to direct future therapeutic approaches. PMID:22961550

Rochester, Lynn; Yarnall, Alison J; Baker, Mark R; David, Rachel V; Lord, Susan; Galna, Brook; Burn, David J

2012-09-01

354

Assessing gait impairment following experimental traumatic brain injury in mice  

PubMed Central

Although gait disturbance is frequently documented among patients with traumatic brain injury (TBI), gait data from animal models of TBI are lacking. To determine the effect of TBI on gait function in adult mice, we assessed gait changes following unilateral controlled cortical impact (CCI) using a computer-assisted automated gait analysis system. Three days after CCI, intensity, area or width of paw contact were significantly decreased in forepaw(s) while the relative paw placement between the fore and hindpaws altered, suggesting that TBI affected sensorimotor status and reduced inter-limb coordination. Similar to TBI patients, CCI decreased gait velocity and stride length, and prolonged stance and swing phase in mice. Following CCI, step pattern was also changed with increasing use in the ipsilateral-diagonal limb sequence. Our results indicate that gait analysis provides great insight into both spatial and temporal aspects of limb function changes during overground locomotion in quadruped species with head injury that are valuable for the purpose of treatment and rehabilitation. Our study also provides additional functional validation for the established mouse CCI model that is relevant to human head injury. PMID:18805438

Neumann, Melanie; Wang, Yonggang; Kim, Sharon; Hong, Shwuhey M.; Bilgen, Mehmet; Liu, Jialing

2008-01-01

355

Assessment of gait after bilateral hip replacement. Case study.  

PubMed

Total hip arthroplasty (THA) is one of the most effective methods of treatment of severe hip osteoarthritis (HOA). In many cases pathological gait patterns persist despite properly conducted surgery and disturb the normal wear of the artificial joint surfaces. The aim of the study was to conduct functional and biomechanical assessment of gait in a patient after bilateral THA due to severe degenerative changes in the hip. The assessment focused on the gait parameters which significantly deviate from a normal gait pattern at various stages of treatment. Physiotherapeutic assessment of the patient included measurements of the range of motion in lower limb joints, the Timed Up and Go test, and pain assessment. Biomechanical assessment involved measurements of spatiotemporal gait parameters and the dynamic range of motion using BTS Smart-E motion analysis system. Although clinical examinations after both the first and second procedure suggested recovery of the patient's physical function, biomechanical assessment of her gait after the second procedure indicated the presence of deviations from a normal gait pattern. Secondary to a limited range of internal/external hip rotation, extension, and abduction, corresponding indices were still in the pathological range. PMID:25041890

Winiarski, S?awomir; Aleksandrowicz, Krzysztof; Jarz?b, S?awomir; Pozowski, Andrzej; Rutkowska-Kucharska, Alicja

2014-01-01

356

Weight set  

NSDL National Science Digital Library

Your skin covers and protects your body. Your skin can also detect pressure and weight. You can tell that a one gram weight feels lighter than a one kilogram weight because the receptors on your skin detect more pressure from a one kilogram weight compared to a one gram weight.

N/A N/A (None; )

2005-12-11

357

Effects of implicit visual feedback distortion on human gait.  

PubMed

Gait rehabilitation after stroke often utilizes treadmill training delivered by either therapists or robotic devices. However, clinical results have shown no benefit from this modality when compared to usual care. On the contrary, results were inferior; perhaps, because in its present form it is not interactive and at least for stroke, central pattern generators at the spinal level do not appear to be the key to promote recovery. To enable gait therapy to be more effective, therapy must be interactive and visual feedback appears to be an important option to engage patients' participation. In this study, we tested healthy subjects to see whether an implicit "visual feedback distortion" influences gait spatial pattern. Subjects were not aware of the visual distortion nor did they realize changes in their gait pattern. The visual feedback of step length symmetry was distorted so that subjects perceived their step length as being asymmetric during treadmill training. We found that a gradual distortion of visual feedback, without explicit knowledge of the manipulation, systematically modulated gait step length away from symmetry and that the visual distortion effect was robust even in the presence of cognitive load. This indicates that although the visual feedback display used in this study did not create a conscious and vivid sensation of self-motion (the properties of the optical flow), experimental modifications of visual information of subjects' movement were found to cause implicit gait modulation. Nevertheless, our results indicate that modulation with visual distortion may require cognitive resources because during the distraction task, the amount of gait modulation was reduced. Our results suggest that a therapeutic program involving visual feedback distortion, in the context of gait rehabilitation, may provide an effective way to help subjects correct gait patterns, thereby improving the outcome of rehabilitation. PMID:22411579

Kim, Seung-Jae; Krebs, Hermano Igo

2012-05-01

358

Concurrent prediction of muscle and tibiofemoral contact forces during treadmill gait.  

PubMed

Detailed knowledge of knee kinematics and dynamic loading is essential for improving the design and outcomes of surgical procedures, tissue engineering applications, prosthetics design, and rehabilitation. This study used publicly available data provided by the "Grand Challenge Competition to Predict in-vivo Knee Loads" for the 2013 American Society of Mechanical Engineers Summer Bioengineering Conference (Fregly et al., 2012, "Grand Challenge Competition to Predict in vivo Knee Loads," J. Orthop. Res., 30, pp. 503-513) to develop a full body, musculoskeletal model with subject specific right leg geometries that can concurrently predict muscle forces, ligament forces, and knee and ground contact forces. The model includes representation of foot/floor interactions and predicted tibiofemoral joint loads were compared to measured tibial loads for two different cycles of treadmill gait. The model used anthropometric data (height and weight) to scale the joint center locations and mass properties of a generic model and then used subject bone geometries to more accurately position the hip and ankle. The musculoskeletal model included 44 muscles on the right leg, and subject specific geometries were used to create a 12 degrees-of-freedom anatomical right knee that included both patellofemoral and tibiofemoral articulations. Tibiofemoral motion was constrained by deformable contacts defined between the tibial insert and femoral component geometries and by ligaments. Patellofemoral motion was constrained by contact between the patellar button and femoral component geometries and the patellar tendon. Shoe geometries were added to the feet, and shoe motion was constrained by contact between three shoe segments per foot and the treadmill surface. Six-axis springs constrained motion between the feet and shoe segments. Experimental motion capture data provided input to an inverse kinematics stage, and the final forward dynamics simulations tracked joint angle errors for the left leg and upper body and tracked muscle length errors for the right leg. The one cycle RMS errors between the predicted and measured tibia contact were 178?N and 168?N for the medial and lateral sides for the first gait cycle and 209?N and 228?N for the medial and lateral sides for the faster second gait cycle. One cycle RMS errors between predicted and measured ground reaction forces were 12?N, 13?N, and 65?N in the anterior-posterior, medial-lateral, and vertical directions for the first gait cycle and 43?N, 15?N, and 96?N in the anterior-posterior, medial-lateral, and vertical directions for the second gait cycle. PMID:24389997

Guess, Trent M; Stylianou, Antonis P; Kia, Mohammad

2014-02-01

359

Transverse plane gait problems in children with cerebral palsy.  

PubMed

Transverse plane deviations are significant contributors to pathologic gait in children with cerebral palsy (CP). Due to limitations in neuromuscular control, balance, strength and coordination, transverse plane gait deviations are poorly tolerated in these children. Transverse plane malalignment results in lever arm dysfunction and can be seen with either intoeing or out-toeing. Frequent causes of transverse plane problems and lever arm dysfunction include long bone (femoral and/or tibial) torsion, pelvic rotation, and pes varus or valgus. Computerized motion analysis facilitates accurate identification of transverse plane abnormalities. This article addresses appropriate identification and treatment of transverse plane gait deviations in children with CP. PMID:23653033

Rethlefsen, Susan A; Kay, Robert M

2013-06-01

360

A robust real-time gait event detection using wireless gyroscope and its application on normal and altered gaits.  

PubMed

Gait events detection allows clinicians and biomechanics researchers to determine timing of gait events, to estimate duration of stance phase and swing phase and to segment gait data. It also aids biomedical engineers to improve the design of orthoses and FES (functional electrical stimulation) systems. In recent years, researchers have resorted to using gyroscopes to determine heel-strike (HS) and toe-off (TO) events in gait cycles. However, these methods are subjected to significant delays when implemented in real-time gait monitoring devices, orthoses, and FES systems. Therefore, the work presented in this paper proposes a method that addresses these delays, to ensure real-time gait event detection. The proposed algorithm combines the use of heuristics and zero-crossing method to identify HS and TO. Experiments involving: (1) normal walking; (2) walking with knee brace; and (3) walking with ankle brace for overground walking and treadmill walking were designed to verify and validate the identified HS and TO. The performance of the proposed method was compared against the established gait detection algorithms. It was observed that the proposed method produced detection rate that was comparable to earlier reported methods and recorded reduced time delays, at an average of 100 ms. PMID:25619613

Gouwanda, Darwin; Gopalai, Alpha Agape

2015-02-01

361

Gait asymmetry in patients with Parkinson's disease and elderly fallers: when does the bilateral coordination of gait require attention?  

PubMed

While it is known that certain pathologies may impact on left-right symmetry of gait, little is known about the mechanisms that contribute to gait symmetry or how high in the hierarchy of the control of gait symmetry is regulated in humans. To assess the contribution of cognitive function to gait symmetry, we measured gait asymmetry (GA) in three subject groups, patients with Parkinson's disease (PD, n = 21), idiopathic elderly fallers (n = 15), and healthy elderly controls (n = 11). All subjects walked, under two walking conditions: usual walking and dual tasking (cognitive loading) condition. For each subject, the swing time (SW) was calculated and averaged across strides for the left and right feet (SWL and SWR). GA was defined as: 100 x /ln(SWR/SWL)/. For both the PD patients and the elderly fallers GA values were significantly higher during the usual walking condition, as compared with the control group (P < 0.01). In addition, for both the PD patients and the elderly fallers, GA significantly increased when they walked and performed a dual task, compared with the usual walking condition (P < 0.003). In contrast, dual tasking did not affect the GA of the healthy controls (P = 0.518). GA was associated with gait speed and gait variability, but no correlations were found between GA and the asymmetry of the classic PD motor symptoms. Thus, the results suggest that the ability to generate a steady, rhythmic walk with a bilaterally coordinated gait does not rely heavily on mental attention and cognitive resources in healthy older adults. In contrast, however, when gait becomes impaired and less automatic, GA apparently relies on cognitive input and attention. PMID:16972073

Yogev, Galit; Plotnik, Meir; Peretz, Chava; Giladi, Nir; Hausdorff, Jeffrey M

2007-03-01

362

The gait variability index: a new way to quantify fluctuation magnitude of spatiotemporal parameters during gait.  

PubMed

This article describes a conglomerate measure of gait variability based on nine spatiotemporal parameters: the Gait Variability Index (GVI). Concurrent validity, inter-session reliability and minimum detectable change (MDC) were evaluated in 31 patients with Friedreich's Ataxia (FRDA), through comparisons with classically used evaluation tools such as the International Cooperative Ataxia Rating Scale (ICARS). GVI scores for the healthy population were 100.3±8.6 and were significantly reduced in FRDA patients (70.4±7.9). The GVI was correlated with the global ICARS score and was sensitive enough to differentiate between groups of FRDA patients categorized by the Posture and Gait Disturbances sub-score. The GVI was found to have a high inter-session reliability with an intraclass correlation coefficient of 0.91. A MDC of 8.6 points was found necessary to ensure that a change in GVI reflects a true change rather than measurement error. The GVI provides a quantitative measure of variability which behaves well statistically in both HP and patients with FRDA. It can be easily implemented using the supplemental data provided with this article. Complementary work is necessary to strengthen the GVI validation. PMID:23889886

Gouelle, Arnaud; Mégrot, Fabrice; Presedo, Ana; Husson, Isabelle; Yelnik, Alain; Penneçot, Georges-François

2013-07-01

363

Gait strategy in genetically obese patients: a 7-year follow up.  

PubMed

The aim of this study was to quantitatively evaluate the change in gait and body weight in the long term in patients with Prader-Willi Syndrome (PWS). Eight adults with PWS were evaluated at baseline and after 7 years. During this period patient participated an in- and out-patient rehabilitation programs including nutritional and adapted physical activity interventions. Two different control groups were included: the first group included 14 non-genetically obese patients (OCG: obese control group) and the second group included 10 age-matched healthy individuals (HCG: healthy control group). All groups were quantitatively assessed during walking with 3D-GA. The results at the 7-year follow-up revealed significant weight loss in the PWS group and spatial-temporal changes in gait parameters (velocity, step length and cadence). With regard to the hip joint, there were significant changes in terms of hip position, which is less flexed. Knee flexion-extension showed a reduction of flexion in swing phase and of its excursion. No changes of the ankle position were evident. As for ankle kinetics, we observed in the second session higher values for the peak of ankle power in terminal stance in comparison to the first session. No changes were found in terms of ankle kinetics. The findings demonstrated improvements associated to long-term weight loss, especially in terms of spatial-temporal parameters and at hip level. Our results back the call for early weight loss interventions during childhood, which would allow the development of motor patterns under normal body weight conditions. PMID:24763375

Cimolin, V; Vismara, L; Galli, M; Grugni, G; Cau, N; Capodaglio, P

2014-07-01

364

Abstract--Inspired by the observation that the cockroach changes the tripod gait to other gait to cross the step, we report  

E-print Network

Abstract--Inspired by the observation that the cockroach changes the tripod gait to other gait to the cockroach's motion, the gait is composed by two stages: rearing stage to lift the front side of the body surfaces [1], adjustment of body posture in the cockroach (Blaberus discoidalis) to climb over obstacles [2

Lin, Pei-Chun

365

Shedding light on walking in the dark: the effects of reduced lighting on the gait of older adults with a higher-level gait disorder and controls  

Microsoft Academic Search

OBJECTIVE: To study the effects of reduced lighting on the gait of older adults with a high level gait disorder (HLGD) and to compare their response to that of healthy elderly controls. METHODS: 22 patients with a HLGD and 20 age-matched healthy controls were studied under usual lighting conditions (1000 lumens) and in near darkness (5 lumens). Gait speed and

Anat Kesler; Gregory Leibovich; Talia Herman; Leor Gruendlinger; Nir Giladi; Jeffrey M Hausdorff

2005-01-01

366

Understanding the complexity of human gait dynamics  

NASA Astrophysics Data System (ADS)

Time series of human gait stride intervals exhibit fractal and multifractal properties under several conditions. Records from subjects walking at normal, slow, and fast pace speed are analyzed to determine changes in the fractal scalings as a function of the stress condition of the system. Records from subjects with different age from children to elderly and patients suffering from neurodegenerative disease are analyzed to determine changes in the fractal scalings as a function of the physical maturation or degeneration of the system. A supercentral pattern generator model is presented to simulate the above two properties that are typically found in dynamical network performance: that is, how a dynamical network responds to stress and to evolution.

Scafetta, Nicola; Marchi, Damiano; West, Bruce J.

2009-06-01

367

Fractal and Multifractal Analysis of Human Gait  

NASA Astrophysics Data System (ADS)

We carried out a fractal and multifractal analysis of human gait time series of young and old individuals, and adults with three illnesses that affect the march: The Parkinson's and Huntington's diseases and the amyotrophic lateral sclerosis (ALS). We obtained cumulative plots of events, the correlation function, the Hurst exponent and the Higuchi's fractal dimension of these time series and found that these fractal markers could be a factor to characterize the march, since we obtained different values of these quantities for youths and adults and they are different also for healthy and ill persons and the most anomalous values belong to ill persons. In other physiological signals there is complexity lost related with the age and the illness, in the case of the march the opposite occurs. The multifractal analysis could be also a useful tool to understand the dynamics of these and other complex systems.

Muñoz-Diosdado, A.; del Río Correa, J. L.; Angulo-Brown, F.

2003-09-01

368

Bearings: Technology and needs  

NASA Technical Reports Server (NTRS)

A brief status report on bearing technology and present and near-term future problems that warrant research support is presented. For rolling element bearings a material with improved fracture toughness, life data in the low Lambda region, a comprehensive failure theory verified by life data and incorporated into dynamic analyses, and an improved corrosion resistant alloy are perceived as important needs. For hydrodynamic bearings better definition of cavitation boundaries and pressure distributions for squeeze film dampers, and geometry optimization for minimum power loss in turbulent film bearings are needed. For gas film bearings, foil bearing geometries that form more nearly optimum film shapes for maximum load capacity, and more effective surface protective coatings for high temperature operation are needed.

Anderson, W. J.

1982-01-01

369

Gait evaluation in hemiparetic patients using subcutaneous peroneal electrical stimulation.  

PubMed

In hemiparetic patients with an implantable peroneal stimulator for correction of drop foot the gait pattern was studied over several years. The gait parameters and M-waves of subcutaneously stimulated muscles were compared with the results obtained before implantation and their variation was observed over time. Of a group of 35 patients with previously implanted electrodes 19 were evaluated. Significant improvements of gait were found although in some cases an excessive eversion of the foot was observed. Nine of these patients had reimplantation because of displacement of the stimulation electrodes after an average time of 3.5 years of proper functioning of the implant. After the reimplantations, similar gait patterns and muscular responses to stimulation were observed as after the initial implantation. PMID:1411357

Kljaji?, M; Malezic, M; A?imovi?, R; Vavken, E; Stanic, U; Pangrsic, B; Rozman, J

1992-09-01

370

Multichannel electrical stimulation of gait in motor disabled patients.  

PubMed

Effects of surface multichannel electrical stimulation of the leg muscles during gait were evaluated by a clinical kinesiological analysis of gait and measurements of average step length, gait velocity, ground reaction forces, and joint angles. Direct effects in 11 stimulated motor disabled patients showed 56% improvement at the kinesiological gait analysis during the stimulation. Long term effects of the multichannel therapy were compared in a threeyear control study with a group of ten nonstimulated patients. At the kinesiological analysis, the stimulated group improved 1.75 times better after 2.5 months of the treatment. The other measurements revealed higher and faster improvement at the stimulated group with a partial decrease of the therapeutic effects after a longer period without treatment. Orthotic multichannel stimulation was indicated after the multichannel therapy in the clinical environment, where the stimulation of proximal leg muscles was favored. PMID:24822543

Malezic, M; Stanic, U; Kljajic, M; Acimovic, R; Krajnik, J; Gros, N; Stopar, M

1984-07-01

371

www.yorku.ca/whgage Gait and Posture Laboratory  

E-print Network

www.yorku.ca/whgage Gait and Posture Laboratory -- Biomechanics at York School of Kinesiology and disease impact an individual's control of their balance when standing and walking. We gather data using

372

Background Subtraction and Target Classification for Gait Recognition  

E-print Network

This paper deals with background modeling and moving object classification for gait recognition. Current image-based human recognition methods such as fingerprints, face, iris biometric modalities, generally require a cooperative subject views. These methods cannot reliably recognize non cooperating individuals at a distance in the real world under changing environmental conditions. In such conditions, recognition of a person using gait has good advantage. First step in gait recognition is the background subtraction/modeling. This is the crucial step in gait recognition. By using this, identification of moving objects from background scene has to be done. Perfect background subtraction is essential to get a high recognition rate. Next step is the separation of human beings from other moving objects (viz; car, tree etc.). In this paper, we have used a modified background subtraction algorithm and subsequently used feature-based classification of pedestrian from other moving objects. Experimental results demonstrated the effectiveness of the proposed method.

Kantipudi Mvv Prasad; Dr. V. Sailaja; A. Jagan

373

Visualising gait symmetry/asymmetry from acceleration data.  

PubMed

Accelerometry-based quantification of gait symmetry/asymmetry is a promising approach for objectively evaluating gait dysfunctions. An important step in the application of this method in clinical settings is to develop reliable gait asymmetry measures and tools for visualising them to create easy-to-understand presentations for both clinicians and patients. This paper describes a new self-adaptive algorithm for estimating motion trajectory from acceleration data and visualising the degree of its asymmetry in 3D space. Two new parameters are introduced to capture asymmetric walking patterns based on the assessment of 3D autocorrelation and biphasicity of the motion trajectory. The performance of our algorithm is confirmed by analysing gait data collected from 245 healthy subjects. The proposed method may be clinically useful in tracking the process of recovering from pathology or injury after rehabilitation. PMID:24266651

Yoneyama, Mitsuru

2015-07-01

374

Wear analysis of unicondylar mobile bearing and fixed bearing knee systems: a knee simulator study.  

PubMed

Unicondylar knee arthroplasty is an attractive alternative to total knee arthroplasty for selected patients with osteoarthritis. Mobile bearing knee designs have been developed to improve knee kinematics, lower contact stresses and reduced wear of ultra-high molecular weight polyethylene compared with fixed bearing designs. This study compared in vitro wear behavior of fixed and mobile unicondylar bearing designs. Analysis was performed using a force-controlled AMTI knee simulator according to ISO 14243-1:2002(E). The wear volume of the implants was determined gravimetrically. Optical surface characterization and an estimation of wear particle size and morphology were performed. Implant kinematic data for both designs were determined. The wear rates averaged 10.7 ± 0.59 mg per 10(6) cycles for the medial and 5.38 ± 0.63 mg per 10(6) cycles for the lateral components of the mobile bearings, compared with 7.51 ± 0.29 mg per 10(6) cycles and 3.04 ± 0.35 mg per 10(6) cycles for the fixed bearings. The mobile bearings therefore exhibited higher wear rates (P<0.01) compared with the fixed bearings. The tibial polyethylene inserts of the mobile bearings showed pronounced backside wear at the inferior surface. The kinematics of both designs was similar. However, anterior-posterior translation was lower in the mobile bearings. The wear particles were mainly elongated and small in size for both designs (P=0.462). This study shows that wear may play an important role in unicondylar mobile bearing knee designs. Advantages of unicondylar mobile designs compared with fixed bearing designs, which have been proposed in terms of wear behavior and improved kinematics, could not be confirmed. PMID:20883831

Kretzer, J Philippe; Jakubowitz, Eike; Reinders, Jörn; Lietz, Eva; Moradi, Babak; Hofmann, Kerstin; Sonntag, Robert

2011-02-01

375

Bear Spray Safety Program  

USGS Publications Warehouse

A bear spray safety program for the U.S. Geological Survey (USGS) was officially initiated by the Firearms Safety Committee to address accident prevention and to promote personnel training in bear spray and its transportation, storage, and use for defense against wild animals. Used as part of a system including firearms, or used alone for those who choose not to carry a firearm, bear spray is recognized as an effective tool that can prevent injury in a wild animal attack.

Blome, C.D.; Kuzniar, R.L.

2009-01-01

376

The Incredible Water Bear  

NSDL National Science Digital Library

This image-rich Micscape Magazine article explores how water bears can be found almost everywhere yet are still unknown to almost everybody, why there are relatively few light microscope photographs of water bears in the literature and on the Web, and how light microscopy can outperform scanning electron microscopy when viewing these animals. It includes a list of historical references, early sketches, and colorful images of water bears, also known as tardigrades.

Mach, Martin; Magazine, Micscape

377

Gait-based Person Recognition Using Arbitrary View Transformation Model.  

PubMed

Gait recognition is a useful biometric trait for person authentication because it is usable even with low image resolution. One challenge is robustness to a view change (crossview matching); view transformation models (VTMs) have been proposed to solve this. VTMs work well if the target views are the same as their discrete training views. However, gait traits are observed from an arbitrary view in a real situation. Thus, target views may not coincide with discrete training views, resulting in recognition accuracy degradation. We propose an arbitrary VTM (AVTM) that accurately matches a pair of gait traits from an arbitrary view. To realize an AVTM, we first construct threedimensional (3D) gait volume sequences of training subjects, disjoint from the test subjects in the target scene. We then generate two-dimensional (2D) gait silhouette sequences of the training subjects by projecting the 3D gait volume sequences onto the same views as the target views, and train the AVTM with gait features extracted from the 2D sequences. In addition, we extend our AVTM by incorporating a part-dependent view selection scheme (AVTM PdVS), which divides the gait feature into several parts, and sets part-dependent destination views for transformation. Because appropriate destination views may differ for different body parts, the part-dependent destination view selection can suppress transformation errors, leading to increased recognition accuracy. Experiments using datasets collected in different settings show that the AVTM improves the accuracy of cross-view matching and that the AVTM PdVS further improves the accuracy in many cases, particularly in verification scenarios. PMID:25423652

Muramatsu, Daigo; Shiraishi, Akira; Makihara, Yasushi; Uddin, Md Zasim; Yagi, Yasushi

2014-11-20

378

Physically active older adults display alterations in gait initiation  

Microsoft Academic Search

An understanding of age-related changes in motor behaviour is important when considering the design of training programs for fall-prevention in the elderly. Gait initiation is a phase of walking during which falls are often provoked and this study compares strategies employed by healthy older and young adults during gait initiation. Twenty-nine older, physically active subjects (65–79 years) and 28 younger

Marketta Henriksson; Helga Hirschfeld

2005-01-01

379

Construction of freezing of gait questionnaire for patients with Parkinsonism  

Microsoft Academic Search

Background: Freezing of gait (FOG) is a common, poorly understood, parkinsonian symptom interfering with daily functioning and quality of life. Assessment of FOG is complex because of the episodic nature of this symptom, and the influence of mental and environmental factors on it.Objective: To design a self-reportable reliable questionnaire for FOG.Method: A questionnaire consisting of 16 items regarding gait and

N. Giladi; H. Shabtai; E. S. Simon; S. Biran; J. Tal; A. D. Korczyn

2000-01-01

380

Bearing restoration by grinding  

NASA Technical Reports Server (NTRS)

A joint program was undertaken by the NASA Lewis Research Center and the Army Aviation Systems Command to restore by grinding those rolling-element bearings which are currently being discarded at aircraft engine and transmission overhaul. Three bearing types were selected from the UH-1 helicopter engine (T-53) and transmission for the pilot program. No bearing failures occurred related to the restoration by grinding process. The risk and cost of a bearing restoration by grinding programs was analyzed. A microeconomic impact analysis was performed.

Hanau, H.; Parker, R. J.; Zaretsky, E. V.; Chen, S. M.; Bull, H. L.

1976-01-01

381

Linear magnetic bearing  

NASA Technical Reports Server (NTRS)

A linear magnetic bearing system having electromagnetic vernier flux paths in shunt relation with permanent magnets, so that the vernier flux does not traverse the permanent magnet, is described. Novelty is believed to reside in providing a linear magnetic bearing having electromagnetic flux paths that bypass high reluctance permanent magnets. Particular novelty is believed to reside in providing a linear magnetic bearing with a pair of axially spaced elements having electromagnets for establishing vernier x and y axis control. The magnetic bearing system has possible use in connection with a long life reciprocating cryogenic refrigerator that may be used on the space shuttle.

Studer, P. A. (inventor)

1983-01-01

382

A novel HMM distributed classifier for the detection of gait phases by means of a wearable inertial sensor network.  

PubMed

In this work, we decided to apply a hierarchical weighted decision, proposed and used in other research fields, for the recognition of gait phases. The developed and validated novel distributed classifier is based on hierarchical weighted decision from outputs of scalar Hidden Markov Models (HMM) applied to angular velocities of foot, shank, and thigh. The angular velocities of ten healthy subjects were acquired via three uni-axial gyroscopes embedded in inertial measurement units (IMUs) during one walking task, repeated three times, on a treadmill. After validating the novel distributed classifier and scalar and vectorial classifiers-already proposed in the literature, with a cross-validation, classifiers were compared for sensitivity, specificity, and computational load for all combinations of the three targeted anatomical segments. Moreover, the performance of the novel distributed classifier in the estimation of gait variability in terms of mean time and coefficient of variation was evaluated. The highest values of specificity and sensitivity (>0.98) for the three classifiers examined here were obtained when the angular velocity of the foot was processed. Distributed and vectorial classifiers reached acceptable values (>0.95) when the angular velocity of shank and thigh were analyzed. Distributed and scalar classifiers showed values of computational load about 100 times lower than the one obtained with the vectorial classifier. In addition, distributed classifiers showed an excellent reliability for the evaluation of mean time and a good/excellent reliability for the coefficient of variation. In conclusion, due to the better performance and the small value of computational load, the here proposed novel distributed classifier can be implemented in the real-time application of gait phases recognition, such as to evaluate gait variability in patients or to control active orthoses for the recovery of mobility of lower limb joints. PMID:25184488

Taborri, Juri; Rossi, Stefano; Palermo, Eduardo; Patanè, Fabrizio; Cappa, Paolo

2014-01-01

383

A Novel HMM Distributed Classifier for the Detection of Gait Phases by Means of a Wearable Inertial Sensor Network  

PubMed Central

In this work, we decided to apply a hierarchical weighted decision, proposed and used in other research fields, for the recognition of gait phases. The developed and validated novel distributed classifier is based on hierarchical weighted decision from outputs of scalar Hidden Markov Models (HMM) applied to angular velocities of foot, shank, and thigh. The angular velocities of ten healthy subjects were acquired via three uni-axial gyroscopes embedded in inertial measurement units (IMUs) during one walking task, repeated three times, on a treadmill. After validating the novel distributed classifier and scalar and vectorial classifiers-already proposed in the literature, with a cross-validation, classifiers were compared for sensitivity, specificity, and computational load for all combinations of the three targeted anatomical segments. Moreover, the performance of the novel distributed classifier in the estimation of gait variability in terms of mean time and coefficient of variation was evaluated. The highest values of specificity and sensitivity (>0.98) for the three classifiers examined here were obtained when the angular velocity of the foot was processed. Distributed and vectorial classifiers reached acceptable values (>0.95) when the angular velocity of shank and thigh were analyzed. Distributed and scalar classifiers showed values of computational load about 100 times lower than the one obtained with the vectorial classifier. In addition, distributed classifiers showed an excellent reliability for the evaluation of mean time and a good/excellent reliability for the coefficient of variation. In conclusion, due to the better performance and the small value of computational load, the here proposed novel distributed classifier can be implemented in the real-time application of gait phases recognition, such as to evaluate gait variability in patients or to control active orthoses for the recovery of mobility of lower limb joints. PMID:25184488

Taborri, Juri; Rossi, Stefano; Palermo, Eduardo; Patanè, Fabrizio; Cappa, Paolo

2014-01-01

384

Balance and gait adaptations in patients with early knee osteoarthritis?  

PubMed Central

Gait adaptations in people with severe knee osteoarthritis (OA) have been well documented, with increased knee adduction moments (KAM) the most commonly reported parameter. Neuromuscular adaptations have also been reported, including reduced postural control. However these adaptations may be the result of morphological changes in the joint, rather than the cause. This study aimed to determine if people with early OA have altered gait parameters and neuromuscular adaptations. Gait and postural tasks were performed by 18 people with early medial knee OA and 18 age and gender-matched control subjects. Parameters measured were kinematics and kinetics during gait and postural tasks, and centre of pressure and electromyographic activity during postural tasks. OA subjects showed no differences in the gait parameters measured, however they demonstrated postural deficits during one-leg standing on both their affected and unaffected sides and altered hip adduction moments compared with controls. Increased activity of the gluteus medius of both sides (p < 0.05), and quadriceps and hamstrings of the affected side (p < 0.05) during one-leg standing compared with controls were also noted. This study has demonstrated that gait adaptations commonly associated with OA do not occur in the early stages, while neuromuscular adaptations are evident. These results may be relevant for early interventions to delay or prevent osteoarthritis in its early stages. PMID:24582072

Duffell, Lynsey D.; Southgate, Dominic F.L.; Gulati, Vivek; McGregor, Alison H.

2014-01-01

385

Changes in in vivo knee contact forces through gait modification.  

PubMed

Knee osteoarthritis (OA) commonly occurs in the medial compartment of the knee and has been linked to overloading of the medial articular cartilage. Gait modification represents a non-invasive treatment strategy for reducing medial compartment knee force. The purpose of this study was to evaluate the effectiveness of a variety of gait modifications that were expected to alter medial contact force. A single subject implanted with a force-measuring knee replacement walked using nine modified gait patterns, four of which involved different hiking pole configurations. Medial and lateral contact force at 25, 50, and 75% of stance phase, and the average value over all of stance phase (0-100%), were determined for each gait pattern. Changes in medial and lateral contact force values relative to the subject's normal gait pattern were determined by a Kruskal-Wallis test. Apart from early stance (25% of stance), medial contact force was most effectively reduced by walking with long hiking poles and wide pole placement, which significantly reduced medial and lateral contact force during stance phase by up to 34% (at 75% of stance) and 26% (at 50% of stance), respectively. Although this study is based on data from a single subject, the results provide important insight into changes in medial and lateral contact forces through gait modification. The results of this study suggest that an optimal configuration of bilateral hiking poles may significantly reduce both medial and lateral compartment knee forces in individuals with medial knee osteoarthritis. PMID:23027590

Kinney, Allison L; Besier, Thor F; Silder, Amy; Delp, Scott L; D'Lima, Darryl D; Fregly, Benjamin J

2013-03-01

386

Accelerometer versus footswitch evaluation of gait unsteadiness and temporal characteristics of gait in two elderly patient groups  

Microsoft Academic Search

We examined anterior-posterior and medio-lateral head and trunk movements during gait using accelerometers, and a footswitch evaluation of temporal gait parameters of elderly fallers with a primary diagnosis of Orthostatic Hypotension, elderly fallers without Orthostatic Hypotension, and a control group of healthy elderly non-fallers. We wanted to evaluate whether both sets of measures can be used to differentiate between patient

A. Barrett; M. O'Connor; K. Culhane; A. M. Finucane; E. Mulkerrin; D. Lyons; G. OLaighin

2008-01-01

387

Body size and walking cadence affect lower extremity joint power in children's gait.  

PubMed

Obese children move less and with greater difficulty than normal-weight counterparts but expend comparable energy. Increased metabolic costs have been attributed to poor biomechanics but few studies have investigated the influence of obesity on mechanical demands of gait. This study sought to assess three-dimensional lower extremity joint powers in two walking cadences in 28 obese and normal-weight children. 3D-motion analysis was conducted for five trials of barefoot walking at self-selected and 30% greater than self-selected cadences. Mechanical power was calculated at the hip, knee, and ankle in sagittal, frontal and transverse planes. Significant group differences were seen for all power phases in the sagittal plane, hip and knee power at weight acceptance and hip power at propulsion in the frontal plane, and knee power during mid-stance in the transverse plane. After adjusting for body weight, group differences existed in hip and knee power phases at weight acceptance in sagittal and frontal planes, respectively. Differences in cadence existed for all hip joint powers in the sagittal plane and frontal plane hip power at propulsion. Frontal plane knee power at weight acceptance and sagittal plane knee power at propulsion were significantly different between cadences. Larger joint powers in obese children contribute to difficulty performing locomotor tasks, potentially decreasing motivation to exercise. PMID:20570152

Shultz, Sarah P; Hills, Andrew P; Sitler, Michael R; Hillstrom, Howard J

2010-06-01

388

Rotordynamics and bearing design of turbochargers  

NASA Astrophysics Data System (ADS)

Turbochargers have gained significant attention in recent years. They are already widely used in automotive, locomotive, and marine applications with diesel engines. They are also applied in the aerospace application to increase the engine performance now. The turbochargers used in automotive and aerospace industry are very light-weight with operating speeds above 100,000 rpm. The turbochargers used in locomotive and marine applications are relatively heavy in size and power compared to the automotive and aerospace applications, and the maximum continuous operating speeds are around 30,000 rpm depending on the diesel engine power rating. Floating ring bushings, semi-floating dampers, ball bearings, and ball bearings with dampers are commonly used in automotive applications for small turbochargers. However, these bearings may not be appropriate for large turbochargers in locomotive and marine applications. Instead, multi-lobed bearings with and without squeeze film dampers are commonly used in these heavy-duty turbochargers. This paper deals with the rotordynamic characteristics of larger turbochargers in locomotive and marine applications. Various bearing designs are discussed. Bearing design parameters are studied and optimal values are suggested. Test results are also presented to support the analytical simulation.

Chen, Wen Jeng

2012-05-01

389

Bearing fatigue investigation 3  

NASA Technical Reports Server (NTRS)

The operating characteristics of large diameter rolling-element bearings in the ultra high speed regimes expected in advanced turbine engines for high performance aircraft were investigated. A high temperature lubricant, DuPont Krytox 143 AC, was evaluated at bearing speeds to 3 million DN. Compared to the results of earlier, similar tests using a MIL-L-23699 (Type II) lubricant, bearings lubricated with the high density Krytox fluid showed significantly higher power requirements. Additionally, short bearing lives were observed when this fluid was used with AISI M50 bearings in an air atmosphere. The primary mode of failure was corrosion initiated surface distress (fatigue) on the raceways. The potential of a case-carburized bearing to sustain a combination of high-tangential and hertzian stresses without experiencing race fracture was also investigated. Limited full scale bearing tests of a 120 mm bore ball bearing at a speed of 25,000 rpm (3 million DN) indicated that a carburized material could sustain spalling fatigue without subsequent propagation to fracture. Planned life tests of the carburized material had to be aborted, however, because of apparent processing-induced material defects.

Nahm, A. H.; Bamberger, E. N.; Signer, H. R.

1982-01-01

390

Hollow rolling element bearings  

NASA Technical Reports Server (NTRS)

A low mass rolling element with a lightweight core and hollow center was developed for use in bearings. The core is plated so as to provide a hard surface and increase the life and reliability of the high speed ball bearings.

Parker, R. J. (inventor)

1973-01-01

391

Grizzly bears and forestry  

Microsoft Academic Search

We assessed the occurrence and fruit production of 13 grizzly bear foods in west-central Alberta, Canada, to better understand use of clearcuts by grizzly bears. Comparisons were made between clearcuts and upland forest stands, while specific models describing food or fruit occurrence within clearcuts were developed from canopy, clearcut age, scarification, and terrain-related variables using logistic regression. Ants, Equisetum spp.,

S. E. Nielsen; R. H. M. Munro; E. L. Bainbridge; G. B. Stenhouse; M. S. Boyce

2004-01-01

392

ALASKAN POLAR BEAR DENNING  

Microsoft Academic Search

Abstract: Information on 35 overwinter maternity dens of Alaskan polar bears (Ursus maritimnus Phipps) and on 101 female polar bears with cubs, recently emerged from dens, was obtained by aerial and ground surveys, interviews with Arctic coast residents, and literature review. Pregnant females form snow dens in October and November and give birth in December and January. Females and cubs

Jack W. Lentfer; Richard J. Hensel

393

Grizzly bears and forestry  

Microsoft Academic Search

Timber harvesting and oil and gas extraction create ecological change beyond just the footprint of the resource extraction. These activities also create a permanent network of roads that can have lasting effects on forest ecology. Grizzly bears (Ursus arctos) suffer higher mortality when in close proximity to roads, yet bears in the foothills of west-central Alberta, continue to use these

C. L. Roever; M. S. Boyce; G. B. Stenhouse

2008-01-01

394

Direct Comparison of Measured and Calculated Total Knee Replacement Force Envelopes during Walking in the Presence of Normal and Abnormal Gait Patterns  

PubMed Central

Knee joint forces measured from instrumented implants provide important information for testing the validity of computational models that predict knee joint forces. The purpose of this study was to validate a parametric numerical model for predicting knee joint contact forces against measurements from four subjects with instrumented TKRs during the stance phase of gait. Model sensitivity to abnormal gait patterns was also investigated. The results demonstrated good agreement for three subjects with relatively normal gait patterns, where the difference between the mean measured and calculated forces ranged from 0.05 to 0.45 body weights, and the envelopes of measured and calculated forces (from three walking trials) overlapped. The fourth subject, who had a “quadriceps avoidance” external moment pattern, initially had little overlap between the measured and calculated force envelopes. When additional constraints were added, tailored to the subject’s gait pattern, the model predictions improved to complete force envelope overlap. Coefficient of multiple determination analysis indicated that the shape of the measured and calculated force waveforms were similar for all subjects (adjusted coefficient of multiple correlation values between 0.88 and 0.92). The parametric model was accurate in predicting both the magnitude and waveform of the contact force, and the accuracy of model predictions was affected by deviations from normal gait patterns. Equally important, the envelope of forces generated by the range of solutions substantially overlapped with the corresponding measured envelope from multiple gait trials for a given subject, suggesting that the variable strategic processes of in vivo force generation are covered by the solution range of this parametric model. PMID:22284431

Lundberg, Hannah J.; Foucher, Kharma C.; Andriacchi, Thomas P.; Wimmer, Markus A.

2012-01-01

395

OTV bearing deflection investigation  

NASA Technical Reports Server (NTRS)

The primary goal of the Bearing Deflectometer Investigation was to gain experience in the use of fiber optic displacement probe technology for bearing health monitoring in a liquid hydrogen turbo pump. The work specified in this Task Order was conducted in conjunction with Air Force Rocket Propulsion Laboratory Contract F04611-86-C-0010. APD conducted the analysis and design coordination to provide a displacement probe design compatible with the XLR-134 liquid hydrogen turbo pump assembly (TPA). Specifications and requirements of the bearing deflectometer were established working with Mechanical Technology Instruments, Inc. (MTI). The TPA design accommodated positioning of the probe to measure outer race cyclic deflections of the pump inlet bearing. The fiber optic sensor was installed as required in the TPA and sensor output was recorded during the TPA testing. Data review indicated that no bearing deflection signature could be differentiated from the inherent system noise. Alternate sensor installations were not investigated, but might yield different results.

Reimer, B. L.; Diepenbrock, R. T.; Millis, M. G.

1993-01-01

396

Conceptual Design and Feasibility of Foil Bearings for Rotorcraft Engines: Hot Core Bearings  

NASA Technical Reports Server (NTRS)

Recent developments in gas foil bearing technology have led to numerous advanced high-speed rotating system concepts, many of which have become either commercial products or experimental test articles. Examples include oil-free microturbines, motors, generators and turbochargers. The driving forces for integrating gas foil bearings into these high-speed systems are the benefits promised by removing the oil lubrication system. Elimination of the oil system leads to reduced emissions, increased reliability, and decreased maintenance costs. Another benefit is reduced power plant weight. For rotorcraft applications, this would be a major advantage, as every pound removed from the propulsion system results in a payload benefit.. Implementing foil gas bearings throughout a rotorcraft gas turbine engine is an important long-term goal that requires overcoming numerous technological hurdles. Adequate thrust bearing load capacity and potentially large gearbox applied radial loads are among them. However, by replacing the turbine end, or hot section, rolling element bearing with a gas foil bearing many of the above benefits can be realized. To this end, engine manufacturers are beginning to explore the possibilities of hot section gas foil bearings in propulsion engines. This overview presents a logical follow-on activity by analyzing a conceptual rotorcraft engine to determine the feasibility of a foil bearing supported core. Using a combination of rotordynamic analyses and a load capacity model, it is shown to be reasonable to consider a gas foil bearing core section. In addition, system level foil bearing testing capabilities at NASA Glenn Research Center are presented along with analysis work being conducted under NRA Cooperative Agreements.

Howard, Samuel A.

2007-01-01

397

Prediction of gait recovery in spinal cord injured individuals trained with robotic gait orthosis  

PubMed Central

Background Motor impairment is a major consequence of spinal cord injury (SCI). Earlier studies have shown that robotic gait orthosis (e.g., Lokomat) can improve an SCI individual’s walking capacity. However, little is known about the differential responses among different individuals with SCI. The present longitudinal study sought to characterize the distinct recovery patterns of gait impairment for SCI subjects receiving Lokomat training, and to identify significant predictors for these patterns. Methods Forty SCI subjects with spastic hypertonia at their ankles were randomly allocated to either control or intervention groups. Subjects in the intervention group participated in twelve 1-hour Lokomat trainings over one month, while control subjects received no interventions. Walking capacity was evaluated in terms of walking speed, functional mobility, and endurance four times, i.e. baseline, 1, 2, and 4 weeks after training, using the 10-Meter-Walking, Timed-Up-and-Go, and 6-Minute-Walking tests. Growth Mixture Modeling, an analytical framework for stratifying subjects based on longitudinal changes, was used to classify subjects, based on their gait impairment recovery patterns, and to identify the effects of Lokomat training on these improvements. Results Two recovery classes (low and high walking capacity) were identified for each clinical evaluation from both the control and intervention groups. Subjects with initial high walking capacity (i.e. shorter Timed-Up-and-Go time, higher 10-Meter-Walking speed and longer 6-Minute-Walking distance) displayed significant improvements in speed and functional mobility (0.033 m/s/week and–0.41 s/week respectively); however no significant change in endurance was observed. Subjects with low walking capacity exhibited no significant improvement. The membership in these two classes—and thus prediction of the subject’s gait improvement trajectory over time—could be determined by the subject’s maximum voluntary torque at the ankle under both plantar-and dorsi-flexion contractions determined prior to any training. Conclusion Our findings demonstrate that subjects responded to Lokomat training non-uniformly, and should potentially be grouped based on their likely recovery patterns using objective criteria. Further, we found that the subject’s ankle torque can predict whether he/she would benefit most from Lokomat training prior to the therapy. These findings are clinically significant as they can help individualize therapeutic programs that maximize patient recovery while minimizing unnecessary efforts and costs. PMID:24661681

2014-01-01

398

Improvements in Sleep Quality and Gait Speed After Cataract Surgery  

PubMed Central

Abstract Background Gait speed and sleep quality are health indices related to longevity and mortality. In the present study, we measured sleep quality, quality of life, gait speed, and visual acuity before and after cataract surgery to evaluate the efficacy of the procedure on systemic health. Methods The study was conducted on 155 patients (93 women; average age 74.8 years) undergoing cataract surgery with the implantation of a yellow soft acrylic lens. Patients were evaluated using the Pittsburgh Sleep Quality Index (PSQI) and the National Eye Institute Visual Function Questionnaire 25 (VFQ-25; vision-related quality of life) before and then 2 and 7 months after surgery. Four-meter gait speed was also determined. Results Of the 155 patients, 68 (43.9%) were classified as poor sleepers (PSQI>5.5) prior to surgery. Significant improvements were noted in sleep 2 months after surgery (p<0.05, paired t-test), but thereafter the improvements were not significant. Prior to surgery, 117 patients (77.0%) were classified as slow walkers (speed<1.0 meter/s). Gait speed increased significantly in these patients 2 months after surgery (p<0.001, paired t-test). Multiple regression analysis revealed significant correlations between the preoperative VFQ-25 score and both PSQI (p<0.05) and gait speed (p<0.001). Postoperative increases in the VFQ-25 score were positively correlated with decreases in the PSQI (p<0.05). Improvements in visual acuity were correlated with improvements in the VFQ-25 score, but not with either PSQI or gait speed. Conclusion Cataract surgery effectively improves sleep quality and slow gait speed. PMID:23145881

Muramatsu, Masahiro; Negishi, Kazuno; Tsubota, Kazuo

2013-01-01

399

Does Anxiety Cause Freezing of Gait in Parkinson's Disease?  

PubMed Central

Individuals with Parkinson's disease (PD) commonly experience freezing of gait under time constraints, in narrow spaces, and in the dark. One commonality between these different situations is that they may all provoke anxiety, yet anxiety has never been directly examined as a cause of FOG. In this study, virtual reality was used to induce anxiety and evaluate whether it directly causes FOG. Fourteen patients with PD and freezing of gait (Freezers) and 17 PD without freezing of gait (Non-Freezers) were instructed to walk in two virtual environments: (i) across a plank that was located on the ground (LOW), (ii) across a plank above a deep pit (HIGH). Multiple synchronized motion capture cameras updated participants' movement through the virtual environment in real-time, while their gait was recorded. Anxiety levels were evaluated after each trial using self-assessment manikins. Freezers performed the experiment on two separate occasions (in their ON and OFF state). Freezers reported higher levels of anxiety compared to Non-Freezers (p<0.001) and all patients reported greater levels of anxiety when walking across the HIGH plank compared to the LOW (p<0.001). Freezers experienced significantly more freezing of gait episodes (p?=?0.013) and spent a significantly greater percentage of each trial frozen (p?=?0.005) when crossing the HIGH plank. This finding was even more pronounced when comparing Freezers in their OFF state. Freezers also had greater step length variability in the HIGH compared to the LOW condition, while the step length variability in Non-Freezers did not change. In conclusion, this was the first study to directly compare freezing of gait in anxious and non-anxious situations. These results present strong evidence that anxiety is an important mechanism underlying freezing of gait and supports the notion that the limbic system may have a profound contribution to freezing in PD. PMID:25250691

Ehgoetz Martens, Kaylena A.; Ellard, Colin G.; Almeida, Quincy J.

2014-01-01

400

General tensor discriminant analysis and gabor features for gait recognition.  

PubMed

The traditional image representations are not suited to conventional classification methods, such as the linear discriminant analysis (LDA), because of the under sample problem (USP): the dimensionality of the feature space is much higher than the number of training samples. Motivated by the successes of the two dimensional LDA (2DLDA) for face recognition, we develop a general tensor discriminant analysis (GTDA) as a preprocessing step for LDA. The benefits of GTDA compared with existing preprocessing methods, e.g., principal component analysis (PCA) and 2DLDA, include 1) the USP is reduced in subsequent classification by, for example, LDA; 2) the discriminative information in the training tensors is preserved; and 3) GTDA provides stable recognition rates because the alternating projection optimization algorithm to obtain a solution of GTDA converges, while that of 2DLDA does not. We use human gait recognition to validate the proposed GTDA. The averaged gait images are utilized for gait representation. Given the popularity of Gabor function based image decompositions for image understanding and object recognition, we develop three different Gabor function based image representations: 1) the GaborD representation is the sum of Gabor filter responses over directions, 2) GaborS is the sum of Gabor filter responses over scales, and 3) GaborSD is the sum of Gabor filter responses over scales and directions. The GaborD, GaborS and GaborSD representations are applied to the problem of recognizing people from their averaged gait images.A large number of experiments were carried out to evaluate the effectiveness (recognition rate) of gait recognition based on first obtaining a Gabor, GaborD, GaborS or GaborSD image representation, then using GDTA to extract features and finally using LDA for classification. The proposed methods achieved good performance for gait recognition based on image sequences from the USF HumanID Database. Experimental comparisons are made with nine state of the art classification methods in gait recognition. PMID:17699917

Tao, Dacheng; Li, Xuelong; Wu, Xindong; Maybank, Stephen J

2007-10-01

401

Touchdown Ball-Bearing System for Magnetic Bearings  

NASA Technical Reports Server (NTRS)

The torque-limited touchdown bearing system (TLTBS) is a backup mechanical-bearing system for a high-speed rotary machine in which the rotor shaft is supported by magnetic bearings in steady-state normal operation. The TLTBS provides ball-bearing support to augment or supplant the magnetic bearings during startup, shutdown, or failure of the magnetic bearings. The TLTBS also provides support in the presence of conditions (in particular, rotational acceleration) that make it difficult or impossible to control the magnetic bearings or in which the magnetic bearings are not strong enough (e.g., when the side load against the rotor exceeds the available lateral magnetic force).

Kingsbury, Edward P.; Price, Robert; Gelotte, Erik; Singer, Herbert B.

2003-01-01

402

Ball and Roller Bearings. A Teaching Reference.  

ERIC Educational Resources Information Center

The manual provides a subject reference for ball and roller bearings. The following topics are included: (1) bearing nomenclature, (2) bearing uses, (3) bearing capacities, (4) shop area working conditions, (5) bearing removal, (6) bearing cleaning and inspection, (7) bearing replacement, (8) bearing lubrication, (9) bearing installation, (10)…

American Association for Vocational Instructional Materials, Athens, GA.

403

A Music Search Engine for Therapeutic Gait Training Zhonghua Li1  

E-print Network

. Music ther- apy offers an alternative treatment method for Parkinson's patients, known as rhythmic to help music therapists provide appropriate music for gait training for Parkinson's patients. Unlike Factors Keywords Music Therapy, Gait Training, Parkinson's Disease 1. INTRODUCTION Parkinson's disease

Wang, Ye

404

Good bearings reduce downtime  

SciTech Connect

Points out that a poorly maintained $100 bearing can hold up the operation of a $1-million conveyor. Of all the moving parts in a coal conveyor system, few cost less or last longer than anti-friction bearings. Most modern conveyor systems are equipped with 2 types of bearings: troughing idlers, spaced at regular intervals to support the conveyor belt as it travels throughout the system, and the adaptermounted spherical roller bearing pillow blocks that are used in the head, tail, bend and takeup pulleys that drive, alter the direction of, or regulate tension in the belt to allow for repairs or splicing. Explains how pillow blocks should handle radial or axial loads, how to mount bearings correctly, and how rings prevent infiltration. Concludes that by making certain that the proper bearing types are built into the system initially, or used as replacements in case of failures, paying close attention to installation procedures and devoting adequate time to maintenance, conveyor system bearings can provide decades of problem-free service.

Kinney, J.; Foster, J.

1982-12-01

405

Positive force feedback in bouncing gaits?  

PubMed Central

During bouncing gaits (running, hopping, trotting), passive compliant structures (e.g. tendons, ligaments) store and release part of the stride energy. Here, active muscles must provide the required force to withstand the developing tendon strain and to compensate for the inevitable energy losses. This requires an appropriate control of muscle activation. In this study, for hopping, the potential involvement of afferent information from muscle receptors (muscle spindles, Golgi tendon organs) is investigated using a two-segment leg model with one extensor muscle. It is found that: (i) positive feedbacks of muscle-fibre length and muscle force can result in periodic bouncing; (ii) positive force feedback (F+) stabilizes bouncing patterns within a large range of stride energies (maximum hopping height of 16.3 cm, almost twofold higher than the length feedback); and (iii) when employing this reflex scheme, for moderate hopping heights (up to 8.8 cm), an overall elastic leg behaviour is predicted (hopping frequency of 1.4-3 Hz, leg stiffness of 9-27 kN m(-1)). Furthermore, F+ could stabilize running. It is suggested that, during the stance phase of bouncing tasks, the reflex-generated motor control based on feedbacks might be an efficient and reliable alternative to central motor commands. PMID:14561282

Geyer, Hartmut; Seyfarth, Andre; Blickhan, Reinhard

2003-01-01

406

The effects of peripheral vascular disease on gait.  

PubMed

This study was designed to determine whether patients with peripheral vascular disease (PVD) have gait abnormalities. A previous study on humans with PVD found no abnormalities whereas significant gait changes were seen with a rat model of PVD. The study population was comprised of 10 controls and 9 subjects with PVD (all male). The PVD group had documented pain in one or both legs while walking. Subjects ranged in age from 55-92 years of age, with a mean age of 69 in the PVD group and 70 in the control group. The GaitMat II system was used to measure both spatial and temporal variables of gait. Subjects walked across the mat, four to six times, at their comfortable walking speed. The PVD group then walked on a treadmill until they experienced moderate claudication pain and felt they had to stop (pain levels between 6 and 8, with maximal pain at level 10). Control group walked on a treadmill for 10 minutes without pain. All subjects repeated the gait tests on the GaitMat H system immediately after treadmill walking. Claudication pain persisted in the PVD group during the second gait test. The PVD group was not different than control group in any of the measured variables on the first test (p values from .35 to .99). Difference scores (post- minus pre-treadmill walking)for PVD group were significantly different than those for control group on 8 of 11 variables (p values <.005). The primary response in PVD subjects was reduced walking speed (1.02+/-0.16 to 0.94+/-0.16 m/s) and reduced step length (0.60+/-0.08 to 0.57+/-0.09 m/s), whereas control subjects increased their speed (1.09+/-0.17 to 1.19+/-0.19 m/s) and step length (0.63+/-0.10 to 0.67+/-0.10 m/s). No asymmetries in gait were measured in either group, either before or after treadmill walking. In conclusion, PVD subjects were not different in gait while rested, but responded to claudication pain by reducing preferred walking speed and step size. PMID:10462161

McCully, K; Leiper, C; Sanders, T; Griffin, E

1999-07-01

407

The Polar Bear Tracker  

NSDL National Science Digital Library

This new Web site from the World Wildlife Fund (WWF) International explores how polar bears are affected by global warming. Data on the movements of two radio-collared bears can be viewed, along with the ice status, through a series of online maps. This is an interesting site with valuable information and a nice balance of maps, photos, and text. The animation of the polar bear tracking data is a really neat feature, but is best viewed by advancing through the stages manually because the rapid speed of the film makes it difficult to comprehend.

2002-01-01

408

Ball Bearing Mechanics  

NASA Technical Reports Server (NTRS)

Load-deflection relationships for different types of elliptical contacts such as those found in a ball bearing are developed. Simplified expressions that allow quick calculations of deformation to be made simply from a knowledge of the applied load, the material properties, and the geometry of the contacting elements are presented. Ball bearings subjected to radial, thrust and combined ball loads are analyzed. A design criterion for fatigue life of ball bearings is developed. The section of a satisfactory lubricant, as well as describing systems that provide a constant flow of lubricant to the contact, is considered.

Hamrock, B. J.; Dowson, D.

1981-01-01

409

Impaired regulation of stride variability in Parkinson's disease subjects with freezing of gait  

Microsoft Academic Search

  \\u000a Patients with Parkinson's disease (PD) often experience freezing of gait, a debilitating phenomenon during which the subject\\u000a suddenly becomes unable to start walking or to continue to move forward. Little is known about the gait of those subjects\\u000a with PD who experience freezing of gait or the pathophysiology of freezing. One possibility is that freezing of gait is a

J. M. Hausdorff; J. D. Schaafsma; Y. Balash; A. L. Bartels; T. Gurevich; N. Giladi

2003-01-01

410

Net Center of Pressure Analysis during Gait Initiation in Patient with Hemiplegia  

Microsoft Academic Search

Gait initiation is a transitional process from the balanced upright standing to the beginning of steady-state walking. Steady-state\\u000a walking represents the start of repeated gait pattern with steady-state walking speed within one gait cycle. Hemiplegic patients’\\u000a gait initiation was analyzed using the 3D motion analysis system synchronized with 2 force plates. The first vertex(V1) in\\u000a the CoP trajectory was placed

S. H. Hwang; S. W. Park; H. S. Choi; Y. H. Kim

411

Principal Component Analysis of gait in Parkinson's disease: relevance of gait velocity.  

PubMed

Principal Component Analysis (PCA) is a method to estimate the relation between data points. We used PCA to analyse movements of the upper and lower extremities during treadmill walking in healthy subjects and two groups of Parkinsonian patients. Healthy subjects (n=35) showed a typical pattern with high values of PC1 and low values in a descending order of PC2-PC4. Increase of speed resulted in a significant increase of PC1 and a significant decrease of the following PC's. In more severely affected patients (n=19, UPDRS>20), PC1 was significantly decreased and PC2-PC4 were significantly increased compared to healthy subjects. Speed could be increased only within a small range without corresponding changes of the PC's. In less severely affected patients (n=17), significant differences of the PC's were only found with fast pace. Separate analysis of arms and legs revealed that these changes are only due to altered movements of the arm. Analysis of the pattern of PC's in response to changes of gait velocities reveal alterations even in less severely affected Parkinsonian patients. The changes of the PC's with higher gait velocities in healthy subjects are suggestive of an increase of intersegmental coordination. This is impaired even in less severely affected Parkinsonian patients. PMID:24374062

Dillmann, Ulrich; Holzhoffer, Claudia; Johann, Yvonne; Bechtel, Sabrina; Gräber, Stefan; Massing, Christoph; Spiegel, Jörg; Behnke, Stefanie; Bürmann, Jan; Louis, Alfred K

2014-03-01

412

Effect of Rhythmic Auditory Stimulation on Gait in Parkinsonian Patients with and without Freezing of Gait  

PubMed Central

Freezing of gait (FOG) in Parkinson's disease (PD) rises in prevalence when the effect of medications decays. It is known that auditory rhythmic stimulation improves gait in patients without FOG (PD-FOG), but its putative effect on patients with FOG (PD+FOG) at the end of dose has not been evaluated yet. This work evaluates the effect of auditory rhythmic stimulation on PD+FOG at the end of dose. 10 PD+FOG and 9 PD-FOG patients both at the end of dose periods, and 10 healthy controls were asked to perform several walking tasks. Tasks were performed in the presence and absence of auditory sensory stimulation. All PD+FOG suffered FOG during the task. The presence of auditory rhythmic stimulation (10% above preferred walking cadence) led PD+FOG to significantly reduce FOG. Velocity and cadence were increased, and turn time reduced in all groups. We conclude that auditory stimulation at the frequency proposed may be useful to avoid freezing episodes in PD+FOG. PMID:20339591

Arias, Pablo; Cudeiro, Javier

2010-01-01

413

Secure and Privacy Enhanced Gait Authentication on Smart Phone  

PubMed Central

Smart environments established by the development of mobile technology have brought vast benefits to human being. However, authentication mechanisms on portable smart devices, particularly conventional biometric based approaches, still remain security and privacy concerns. These traditional systems are mostly based on pattern recognition and machine learning algorithms, wherein original biometric templates or extracted features are stored under unconcealed form for performing matching with a new biometric sample in the authentication phase. In this paper, we propose a novel gait based authentication using biometric cryptosystem to enhance the system security and user privacy on the smart phone. Extracted gait features are merely used to biometrically encrypt a cryptographic key which is acted as the authentication factor. Gait signals are acquired by using an inertial sensor named accelerometer in the mobile device and error correcting codes are adopted to deal with the natural variation of gait measurements. We evaluate our proposed system on a dataset consisting of gait samples of 34 volunteers. We achieved the lowest false acceptance rate (FAR) and false rejection rate (FRR) of 3.92% and 11.76%, respectively, in terms of key length of 50 bits. PMID:24955403

Choi, Deokjai

2014-01-01

414

Gait-based gender classification using mixed conditional random field.  

PubMed

This paper proposes a supervised modeling approach for gait-based gender classification. Different from traditional temporal modeling methods, male and female gait traits are competitively learned by the addition of gender labels. Shape appearance and temporal dynamics of both genders are integrated into a sequential model called mixed conditional random field (CRF) (MCRF), which provides an open framework applicable to various spatiotemporal features. In this paper, for the spatial part, pyramids of fitting coefficients are used to generate the gait shape descriptors; for the temporal part, neighborhood-preserving embeddings are clustered to allocate the stance indexes over gait cycles. During these processes, we employ evaluation functions like the partition index and Xie and Beni's index to improve the feature sparseness. By fusion of shape descriptors and stance indexes, the MCRF is constructed in coordination with intra- and intergender temporary Markov properties. Analogous to the maximum likelihood decision used in hidden Markov models (HMMs), several classification strategies on the MCRF are discussed. We use CASIA (Data set B) and IRIP Gait Databases for the experiments. The results show the superior performance of the MCRF over HMMs and separately trained CRFs. PMID:21622075

Hu, Maodi; Wang, Yunhong; Zhang, Zhaoxiang; Zhang, De

2011-10-01

415

Accurate and Reliable Gait Cycle Detection in Parkinson's Disease.  

PubMed

There is a growing interest in the use of Inertial Measurement Unit (IMU)-based systems that employ gyroscopes for gait analysis. We describe an improved IMU-based gait analysis processing method that uses gyroscope angular rate reversal to identify the start of each gait cycle during walking. In validation tests with six subjects with Parkinson disease (PD), including those with severe shuffling gait patterns, and seven controls, the probability of True-Positive event detection and False-Positive event detection was 100% and 0%, respectively. Stride time validation tests using high-speed cameras yielded a standard deviation of 6.6 ms for controls and 11.8 ms for those with PD. These data demonstrate that the use of our angular rate reversal algorithm leads to improvements over previous gyroscope-based gait analysis systems. Highly accurate and reliable stride time measurements enabled us to detect subtle changes in stride time variability following a Parkinson's exercise class. We found unacceptable measurement accuracy for stride length when using Aminian and colleague's gyro-based biomechanical algorithm, with errors as high as 30% in PD subjects. An alternative method, using synchronized infrared timing gates to measure velocity, combined with accurate mean stride time from our angular rate reversal algorithm, more accurately calculates mean stride length. PMID:24158491

Hundza, Sandra; Hook, William; Harris, Christopher; Mahajan, Sunny; Leslie, Paul; Spani, Carl; Spalteholz, Leonhard; Birch, Benjamin; Commandeur, Drew; Livingston, Nigel

2013-10-22

416

Analysis of foot load during ballet dancers' gait.  

PubMed

Ballet is an art that puts extreme demands on the dancer's musculoskeletal system and therefore significantly affects motor behavior of the dancers. The aim of our research was to compare plantar pressure distribution during stance phase of gait between a group of professional ballet dancers and non-dancers. Thirteen professional dancers (5 men, 8 women; mean age of 24.1 ± 3.8 years) and 13 nondancers (5 men, 8 women; mean age of 26.1 ± 5.3 years) participated in this study. Foot pressure analysis during gait was collected using a 2 m pressure plate. The participants were instructed to walk across the platform at a self-selected pace barefoot. Three gait cycles were necessary for the data analysis. The results revealed higher (p < 0.05) pressure peaks in medial edge of forefoot during gait for dancers in comparison with nondancers. Furthermore, differences in total foot loading and foot loading duration of rearfoot was higher (p < 0.05) in dancers as well. We can attribute these differences to long-term and intensive dancing exercises that can change the dancer's gait stereotype. PMID:25088458

Prochazkova, Marketa; Tepla, Lucie; Svoboda, Zdenek; Janura, Miroslav; Cieslarová, Miloslava

2014-01-01

417

[Freezing of gait in patients with Parkinson's disease.  

PubMed

Objective. Freezing of gait (FOG) are the brief episodes of voluntary movement blocks in Parkinson`s disease and other variants of parkinsonism, which limit patient's mobility and decrease quality of life. Pathogenesis of FOG is still unclear. Authors studied characteristics of FOG in different stages of PD. Material and methods. Seventy patients were examined using different scales for assessment of clinical features. We measured the length, speed and cadence of gait and carried out a kinematic analysis of movements and stabilometry. Results and conclusion. FOG were found in 34.3% patients with PD, most of them were in advanced and late stages. FOG in off-periods were observed in 2/3 patients treated with levodopa, 1/3 of patients did not relate FOG with the periods of levodopa action. Turn and start FOG were noted more often. In patients with FOG, there were more expressed Parkinson's signs, especially axial symptoms, and more frequent urination disorders. The reduced speed of gait and asymmetry of gait were found as well. The kinematic analysis of gait revealed a correlation between the frequency of FOG and periods of support (and double support). PMID:25042502

Skripkina, N A; Levin, O S

2014-01-01

418

Portable activity monitoring system for temporal parameters of gait cycles.  

PubMed

A portable and wireless activity monitoring system was developed for the estimation of temporal gait parameters. The new system was built using three-axis accelerometers to automatically detect walking steps with various walking speeds. The accuracy of walking step-peak detection algorithm was assessed by using a running machine with variable speeds. To assess the consistency of gait parameter analysis system, estimated parameters, such as heel-contact and toe-off time based on accelerometers and footswitches were compared for consecutive 20 steps from 19 individual healthy subjects. Accelerometers and footswitches had high consistency in the temporal gait parameters. The stance, swing, single-limb support, and double-limb support time of gait cycle revealed ICCs values of 0.95, 0.93, 0.86, and 0.75 on the right and 0.96, 0.86, 0.93, 0.84 on the left, respectively. And the walking step-peak detection accuracy was 99.15% (±0.007) for the proposed method compared to 87.48% (±0.033) for a pedometer. Therefore, the proposed activity monitoring system proved to be a reliable and useful tool for identification of temporal gait parameters and walking pattern classification. PMID:20703612

Lee, Jung-Ah; Cho, Sang-Hyun; Lee, Young-Jae; Yang, Heui-Kyung; Lee, Jeong-Whan

2010-10-01

419

Dynamic markers of altered gait rhythm in amyotrophic lateral sclerosis  

NASA Technical Reports Server (NTRS)

Amyotrophic lateral sclerosis (ALS) is a disorder marked by loss of motoneurons. We hypothesized that subjects with ALS would have an altered gait rhythm, with an increase in both the magnitude of the stride-to-stride fluctuations and perturbations in the fluctuation dynamics. To test for this locomotor instability, we quantitatively compared the gait rhythm of subjects with ALS with that of normal controls and with that of subjects with Parkinson's disease (PD) and Huntington's disease (HD), pathologies of the basal ganglia. Subjects walked for 5 min at their usual pace wearing an ankle-worn recorder that enabled determination of the duration of each stride and of stride-to-stride fluctuations. We found that the gait of patients with ALS is less steady and more temporally disorganized compared with that of healthy controls. In addition, advanced ALS, HD, and PD were associated with certain common, as well as apparently distinct, features of altered stride dynamics. Thus stride-to-stride control of gait rhythm is apparently compromised with ALS. Moreover, a matrix of markers based on gait dynamics may be useful in characterizing certain pathologies of motor control and, possibly, in quantitatively monitoring disease progression and evaluating therapeutic interventions.

Hausdorff, J. M.; Lertratanakul, A.; Cudkowicz, M. E.; Peterson, A. L.; Kaliton, D.; Goldberger, A. L.

2000-01-01

420

A comparative collision-based analysis of human gait  

PubMed Central

This study compares human walking and running, and places them within the context of other mammalian gaits. We use a collision-based approach to analyse the fundamental dynamics of the centre of mass (CoM) according to three angles derived from the instantaneous force and velocity vectors. These dimensionless angles permit comparisons across gait, species and size. The collision angle ?, which is equivalent to the dimensionless mechanical cost of transport CoTmech, is found to be three times greater during running than walking of humans. This threefold difference is consistent with previous studies of walking versus trotting of quadrupeds, albeit tends to be greater in the gaits of humans and hopping bipeds than in quadrupeds. Plotting the collision angle ? together with the angles of the CoM force vector ? and velocity vector ? results in the functional grouping of bipedal and quadrupedal gaits according to their CoM dynamics—walking, galloping and ambling are distinguished as separate gaits that employ collision reduction, whereas trotting, running and hopping employ little collision reduction and represent more of a continuum that is influenced by dimensionless speed. Comparable with quadrupedal mammals, collision fraction (the ratio of actual to potential collision) is 0.51 during walking and 0.89 during running, indicating substantial collision reduction during walking, but not running, of humans. PMID:24089334

Lee, David V.; Comanescu, Tudor N.; Butcher, Michael T.; Bertram, John E. A.

2013-01-01

421

Human odometry verifies the symmetry perspective on bipedal gaits.  

PubMed

Bipedal gaits have been classified on the basis of the group symmetry of the minimal network of identical differential equations (alias cells) required to model them. Primary gaits are characterized by dihedral symmetry, whereas secondary gaits are characterized by a lower, cyclic symmetry. This fact was used in a test of human odometry. Results suggest that when distance is measured and reported by gaits from the same symmetry class, primary and secondary gaits are comparable. Switching symmetry classes at report compresses (primary to secondary) or inflates (secondary to primary) measured distance, with the compression and inflation equal in magnitude. Lessons are drawn from modeling the dynamics of behaviors executed in parallel (e.g., interlimb coordination) to model the dynamics of human odometry, in which the behaviors are executed sequentially. The major observations are characterized in terms of a dynamics of sequentially coupled measure and report phases, with relative velocity as an order parameter, or equilibrium state, and difference in symmetry class as an imperfection parameter, or detuning, of that dynamic. PMID:22506786

Turvey, M T; Harrison, Steven J; Frank, Till D; Carello, Claudia

2012-08-01

422

Abstract--In this paper, we explore the mechanical behavior of the knee during the weight acceptance stage of  

E-print Network

the execution of gait, including supporting the body weight and deceleration during the stance phase (bya Abstract-- In this paper, we explore the mechanical behavior of the knee during the weight acceptance stage of stance during normal walking. We show that the torque/angle behavior of the knee during

Dollar, Aaron M.

423

High speed hybrid bearing comprising a fluid bearing and a rolling bearing convected in series  

NASA Technical Reports Server (NTRS)

A description is given of an antifriction bearing and a process by which its fatigue life may be extended. The method involves a rotating shaft supported by a fluid bearing and a rolling element bearing coupled in series. Each bearing turns at a fraction of the rotational speed of the shaft. The fluid bearing is preferably conical, thereby providing thrust and radial load support in a single bearing structure.

Anderson, W. J. (inventor)

1973-01-01

424

Research on Insect Gait Pattern Classification Based on Image Feature Extraction  

Microsoft Academic Search

In this paper, we design a centrifuge system which is based on high-speed image detecting of moving object, to test insect's gait under different conditions. From the statistics of the result, we analysis classification regulation of insects gait mode, and the paper proposed an algorithm based on image feature extraction. Using for reference of achievements of human gait research, we

He Bin; Yu Peng; Yue Ji-guang

2007-01-01

425

Computerized Visual Feedback: An Adjunct to Robotic-Assisted Gait Training  

Microsoft Academic Search

Background and Purpose. Robotic devices for walking rehabilitation allow new possibilities for providing performance-related information to patients during gait training. Based on motor learning principles, augmented feedback during robotic- assisted gait training might improve the rehabilitation process used to regain walking function. This report presents a method to provide visual feedback implemented in a driven gait orthosis (DGO). The purpose

Raphael Banz; Marc Bolliger; Gery Colombo; Volker Dietz; Lars Lunenburger

2008-01-01

426

Sensory cueing effects on maximal speed gait initiation in persons with Parkinson's disease and healthy elders  

Microsoft Academic Search

Researchers have suggested that sensory cues can improve gait initiation in persons with Parkinson's disease (PD); however, there is little research that documents the effects of sensory cues on gait initiation. The purpose of this study was to examine the effects of auditory and cutaneous sensory cues on maximal speed gait initiation in person's with PD and healthy elderly. Seven

Leland E Dibble; Diane E Nicholson; Barry Shultz; Bruce A MacWilliams; Robin L Marcus; Carolee Moncur

2004-01-01

427

RESEARCH ARTICLE Open Access Differences in gait characteristics between total hip,  

E-print Network

RESEARCH ARTICLE Open Access Differences in gait characteristics between total hip, knee, and ankle arthroplasty (THA), total knee arthroplasty (TKA) and total ankle arthroplasty (TAA) with a group of healthy side-to-side asymmetries in gait characteristics. Keywords: Gait, Arthroplasty, Hip, Knee, Ankle

Boyer, Edmond

428

Gait analysis in idiopathic normal pressure hydrocephalus – which parameters respond to the CSF tap test?  

Microsoft Academic Search

Objectives: Normal pressure hydrocephalus (NPH) is an often underestimated cause of hypokinetic gait disorders in the elderly. Diagnosing NPH is a complex problem, since many symptoms overlap with other neurological diseases. The purpose of the present study was to characterize the gait pattern in NPH quantitatively. Additionally, we analyzed the improvement of gait parameters following tapping of cerebrospinal fluid (CSF).Methods:

H Stolze; J. P Kuhtz-Buschbeck; H Drücke; K Jöhnk; C Diercks; S Palmié; H. M Mehdorn; M Illert; G Deuschl

2000-01-01

429

Assessment of spatio-temporal gait parameters from trunk accelerations during human walking  

Microsoft Academic Search

This paper studies the feasibility of an analysis of spatio-temporal gait parameters based upon accelerometry. To this purpose, acceleration patterns of the trunk and their relationships with spatio-temporal gait parameters were analysed in healthy subjects. Based on model predictions of the body's centre of mass trajectory during walking, algorithms were developed to determine spatio- temporal gait parameters from trunk acceleration

Wiebren Zijlstra

2003-01-01

430

Sensory perception of unexpected sudden changes in floor level during human gait  

Microsoft Academic Search

Possible clues for sensory perception of an unexpected sudden change in floor level during human gait could be discrepancies in the time of heel contact, location of force application point (center of pressure, CoP) in the sole at the heel contact and subsequent stance period from the ones prescribed prior to the gait execution prepared for the normal level gait,

Tatsuya Ishikawa; Yuji Kaji; Taishin Nomura

2006-01-01

431

A normative sample of temporal and spatial gait parameters in children using the GAITRite ® electronic walkway  

Microsoft Academic Search

PurposeThe purpose of this study was to develop a normative sample of temporal and spatial gait parameters for children (ages 1–10 years) using the GAITRite® electronic walkway. Reliability of the GAITRite® for assessing gait in children is similar to its reliability in adults. Normative temporal and spatial gait parameters have not been published using the GAITRite® limiting clinicians and researchers

Stacey C. Dusing; Deborah E. Thorpe

2007-01-01

432

Gait Pattern Differences between Children with Mild Scoliosis and Children with Unilateral Cerebral Palsy  

PubMed Central

This study was conducted to investigate the effects of asymmetrical body posture alone, i.e., the effects seen in children with mild scoliosis, vs. the effects of body posture control impairment, i.e., those seen in children with unilateral cerebral palsy on gait patterns. Three-dimensional instrumented gait analysis (3DGA) was conducted in 45 children with hemiplegia and 51 children with mild scoliosis. All the children were able to walk without assistance devices. A set of 35 selected spatiotemporal gait and kinematics parameters were evaluated when subjects walked on a treadmill. A cluster analysis revealed 3 different gait patterns: a scoliotic gait pattern and 2 different hemiplegic gait patterns. The results showed that the discrepancy in gait patterns was not simply a lower limb kinematic deviation in the sagittal plane, as expected. Additional altered kinematics, such as pelvic misorientation in the coronal plane in both the stance and swing phases and inadequate stance phase hip ad/abduction, which resulted from postural pattern features, were distinguished between the 3 gait patterns. Our study provides evidence for a strong correlation between postural and gait patterns in children with unilateral cerebral palsy. Information on differences in gait patterns may be used to improve the guidelines for early therapy for children with hemiplegia before abnormal gait patterns are fully established. The gait pathology characteristic of scoliotic children is a potential new direction for treating scoliosis that complements the standard posture and walking control therapy exercises with the use of biofeedback. PMID:25089908

Domagalska-Szopa, Ma?gorzata; Szopa, Andrzej

2014-01-01

433

Computational Intelligence in Gait Research: A Perspective on Current Applications and Future Challenges  

Microsoft Academic Search

Our mobility is an important daily requirement so much so that any disruption to it severely degrades our perceived quality of life. Studies in gait and human movement sciences, there- fore, play a significant role in maintaining the well-being of our mobility. Current gait analysis involves numerous interdependent gait parameters that are difficult to adequately interpret due to the large

Daniel T. H. Lai; Rezaul K. Begg; Marimuthu Palaniswami

2009-01-01

434

Obstacle Avoidance of Snake Robot Moving with A Novel Gait Using Two-Level PID Controller  

Microsoft Academic Search

In this paper, we introduce a novel locomotion mode (gait) for 2D snake robots. The idea behind this new gait is to control orientation of snake robot by head link and use other links as a means of driving the robot. When snake robot moves using this gait, head link always looks at direction of motion and can therefore receive

Shahir Hasanzadeh; Ali Akbarzadeh Tootoonchi

2008-01-01

435

Altered fractal dynamics of gait: reduced stride-interval correlations with aging and Huntington's disease  

E-print Network

Altered fractal dynamics of gait: reduced stride-interval correlations with aging and Huntington fractal dynamics of gait: reduced stride-interval correlations with aging and Hunting- ton's disease. J. Appl. Physiol. 82(1): 262­269, 1997.-- Fluctuations in the duration of the gait cycle (the stride

436

Human Identification Using Gait and Face Rama Chellappa Amit K. Roy-Chowdhury Shaohua Kevin Zhou  

E-print Network

Human Identification Using Gait and Face Rama Chellappa Amit K. Roy-Chowdhury Shaohua Kevin Zhou face and gait. Gait recognition is related to the broader problem of human motion modeling, which has the goal has been to understand human motion with applications in sports, medicine, elderly care and early

Chowdhury, Amit K. Roy

437

Executive functions are associated with gait and balance in community-living elderly people  

Microsoft Academic Search

BACKGROUND: Cognition influences gait and balance in elderly people. Executive functions seem to play a key role in this mechanism. Previous studies used only a single test to probe executive functions, and outcome measures were restricted to gait variables. We extend this prior work by examining the association between two different executive functions and measures of both gait and balance,

Marianne B. van Iersel; Roy P. C. Kessels; Bastiaan R. Bloem; M. G. M. Olde Rikkert

2008-01-01

438

Corpus callosum atrophy is associated with gait disorders in patients with leukoaraiosis  

Microsoft Academic Search

Cognitive impairment and gait disturbances are the most frequent clinical findings in patients with leukoaraiosis (LA). Corpus callosum (CC) atrophy has been associated with dementia in patients with LA, as well as with gait disturbances in patients with normal pressure hydrocephalus. We investigated, in patients with LA, the possible association between gait impairment and CC atrophy, taking into account cognitive

M. Moretti; G. Carlucci; A. Di Carlo; C. Fonda; M. Prieto; S. Mugnai; L. Bracco; C. Piccini; G. Pracucci; D. Inzitari

2005-01-01

439

Gait and Subcortical Hyperintensities in Mild Alzheimer’s Disease and Aging  

Microsoft Academic Search

Background\\/Aims: The relationship between subcortical hyperintensities (SH) on brain MRI and gait parameters in aging and Alzheimer’s disease (AD) is unclear. This study compared gait in 42 mild AD patients to 22 normal controls (NC) based on their SH severity and correlated them to SH burden in these groups. Methods: Gait velocity, stride length, cadence and step width were captured

Neelesh K. Nadkarni; William E. McIlroy; Elysha Mawji; Sandra E. Black

2009-01-01

440

Systematic review of quantitative clinical gait analysis in patients with dementia  

Microsoft Academic Search

Summary. Introduction: Diminished mobility often accompanies dementia and has a great impact on independence and quality of life. New treatment strategies for dementia are emerging, but the effects on gait remains to be studied objectively. In this review we address the general effects of dementia on gait as revealed by quantitative gait analysis. Methods: A systematic literature search with the

M. B. van Iersel; W. Hoefsloot; M. Munneke; B. R. Bloem; M. G. M. Olde Rikkert

2004-01-01

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